Conjugate molecules which include photosensitizer compositions conjugated to non-antibody non-affinity pair targeting moieties and methods of making and using such conjugates are described.

SUMMARY OF THE INVENTION

The inventor has discovered that classes of molecules not hither to used as targeting moieties for photosensitizers, can be used to target photosensitizers.

Accordingly, the invention features, a conjugate molecule which includes a photosensitizer coupled to a non-pair member (NPM) moiety, e.g., an NPM-polypeptide.

In embodiments in which the targeting moiety includes a polypeptide, the targeting moiety can be a linear, branched, or cyclic polypeptide.

In preferred embodiments, the targeting moiety includes a small anti-microbial peptide (SAMP). Histatins, defensins, cecropins, magainins, Gram positive bacteriocins, and peptide antibiotics can be SAMP's. In preferred embodiments, the targeting moiety includes a bacterial, fungal, animal, e.g., mammalian, e.g., human, SAMP, or an active fragment or analog thereof.

In preferred embodiments the targeting moiety includes a defensin, or an active fragment or analog thereof. By way of example the defensin can be: a human defensin, e.g., HNP-1, -2, -3, or -4; a guinea pig defensin, e.g., GPNP; a rabbit defensin, e.g., rabbit NP-1, -2, -3A, -3B, or 5; a rat defensin, e.g., rat NP-1, -2, -3, or -4; murine cryptin; bovine granulocyte bactenecin or indolicidin; or bovine seminal plasmin.

In preferred embodiments, the targeting moiety includes a SAMP of insect origin, or an active fragment or analog thereof, e.g., a cecropin from Cecropia moths, bumble bees, fruit flies, or other insects, an apidaecin from honeybees, or an adropin from fruit flies.

In preferred embodiments, the targeting moiety includes a SAMP of amphibial origin, or an active fragment or analog thereof, e.g., a magainin, a PGLA, a XPF, a LPF, a CPG, a PGQ, a bombinin, a bombinin-like peptide BLP-1, -2, -3, or -4, or a brevinin.

In preferred embodiments the targeting moiety includes a SAMP from an invertebrate, or an active fragment, or analog thereof, e.g., tachyplesin I, II, or III, or polyphemusin I or II, from horseshoe crab. In preferred embodiments, the targeting moiety is from a fish, e.g., pardaxin.

In preferred embodiments, the targeting moiety includes a bacteriocin, more preferably a Gram positive bacteriocin, or an active fragment, or analog thereof, e.g., a nisin, a subtilin, epidermin, gallidermin, salivarin, or a lacticin.

In preferred embodiments, the targeting moiety includes a peptide antibiotic, or an active fragment or analog thereof, e.g., a tyrocidin, or a bacitracin.

In preferred embodiments the targeting moiety includes a histatin, or an active fragment or analog thereof, e.g., histatin-1 through -8, preferably histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In preferred embodiments, the targeting moiety includes a polypeptide having an affinity for a polysaccharide target, e.g., a lectin. By way of example the lectin can be a seed, bean, root, bark, seaweed, fungal, bacteria, or invertebrate lectin. In preferred embodiments, the targeting moiety includes a plant polypeptide, e.g., a lectin from jack bean, e.g., concanavalin A, or a lectin from a lentil, Lens culinaris.

In preferred embodiments, the targeting moiety includes a salivary polypeptide, or an active fragment or analog thereof. Examples of salivary polypeptides are the histatins, e.g., histatin-1 through -8, or more preferably, histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In preferred embodiments, the targeting moiety includes a Gram negative bacteriocin, e.g., colicin B, colicin E1, or colicin Ia.

In preferred embodiments the targeting moiety includes bacterially elaborated polypeptide, e.g., nisin, subtilin, epidermin, gallidermin, salivarin, or lacticin.

In preferred embodiments the targeting moiety includes a molecule, e.g., a peptide, other than an antibody or either member of a receptor-ligand pair.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In preferred embodiments the targeting moiety includes a peptide in which at least 10, 20, 30, 40, 50, 60, 70, 80, 90% of the amino acid residues are of one amino acid residue, e.g., a positively charged amino acid residue, e.g., a lysine reside, an arginine residue, or an ornithine residue. Particularly preferred targeting moieties are polyamino acids, e.g., polylysine, polyarginine, or polyornithine.

In preferred embodiments the targeting moiety: is cationic; has a net positive charge of +1, +2 or +3 per molecule; has a net positive charge equal to or greater than +4; includes a positively charged amino acid residue, e.g, lysine; includes at least 2, 3, 4, or more positively charged amino acid residues, e.g, a lysine, arginine, or ornithine residue.

In other embodiments the targeting moiety: is anionic; has a net negative charge of -1, -2 or -3 per molecule; has a net negative charge equal to or greater than -4; includes a negatively charged amino acid residue, e.g, aspartic acid or glutamic acid; includes at least 2, 3, 4, or more negatively charged amino acid residues, e.g, glutamic; includes at least 10, 20, 30, 40, or 50% or more negatively charged amino acid residues, e.g, aspartic acid, or glutamic acid.

In preferred embodiments the targeting moiety: is approximately neutral in charge; includes at least 50, 60, 70, 80, or 90% amino acid residues which are neutral amino acid residues, such as serine, threonine, alanine, methionine, cysteine, or valine.

In preferred embodiments the targeting moiety has a molecular weight of more than 1200, 1800, 2400, 3000, 6000, 10,000, 25,000, 50,000, 100,000, or 200,000 daltons. In preferred embodiments the targeting moiety has a molecular weight of less than 250,000, 150,000, 60,000, 25,000, 10,000, 8,000, or 6,000 daltons. In particularly preferred embodiments the molecular weight of the targeting moiety is between 300 and 1800, 600 and 2400, 1200 and 6,000, 5,000 and 8,000, 8,000 and 15,000, 15,000 and 30,000, 35,000 and 70,000, 70,000 and 150,000, or 150,000 and 300,000 daltons.

In preferred embodiments the targeting moiety includes a peptide at least 3, 6, 12, 18, 24, 30, 60, 100, 250, 500, 1,000, or 2,500 residues in length. In preferred embodiments the targeting moiety is a peptide less than 3,000, 1,500, 700, 300, 150, 100, 80, 60,40, 30, or 15 residues in length. In particularly preferred embodiments the targeting moiety includes a peptide of between 6 and 15, 12 and 18, 18 and 30, 20 and 40, 30 and 60, 80 and 120, 150 and 300, 300 and 600, 800 and 1,200, or 2,000 and 3,000 residues in length.

In preferred embodiments the targeting moiety includes a protein which forms a pore in the permeability barrier of the target organism, e.g., in Staphylococcus aureus, Klebsiella pneumoniae, Candida albicans, Leishmania donovani, or Giardia lamblia.

In other preferred embodiments, the targeting moiety includes a low density lipoprotein, a high density lipoprotein or a very low density lipoprotein.

In preferred embodiments, the targeting moiety has been selected using a surface molecule of the target organism as an affinity selection or screen, e,g, the targeting moiety has been selected in a chemical or phage display library.

In particularly preferred embodiments the targeting moiety includes a polylysine molecule. The polylysine can be between 6 and 15, 12 and 18, 18 and 30, 20 and 40, 30 and 60, 80 and 120, 150 and 300, 300 and 600, 800 and 1,200, or 2,000 and 3,000 residues in length.

In preferred embodiments the targeting moiety includes a polypeptide, e.g., a polyamino acid, which has been chemically modified to alter its charge, e.g., the charge of side chains of one or more amino acid residues of the polyamino acid. For example, one or more, or approximately 10, 25, 50, 75, 90 or 100% of the charged side chains can be modified. By modified is meant that a negative side chain, e.g., a glutamic acid, or an aspartic acid, side chain is made positive or neutral in charge, a positively charged side chain, e.g., the side chain of lysine, arginine, or ornithine is made negative or neutral in charge. By way of example, one or more of the side chains of polylysine can be made neutral or negative in charge.

In preferred embodiments: the photosensitizer produces singlet oxygen upon absorption of electromagnetic irradiation at the proper energy level and wavelength; the photosensitizer includes a porphyrin or porphyrin derivative; the photosensitizer includes chlorin e6 or a chlorin derivative.

In preferred embodiments the conjugate further includes a backbone member. In such embodiments the backbone is coupled both to a photosensitizer and to a targeting moiety. The backbone can itself also be a targeting moiety, e.g. polylysine.

In preferred embodiments, the conjugate molecule has affinity for a target organism. The target organism, by way of example, can be: a microorganism, e.g., a bacterial cell, a fungal cell, a protozoan cell, a cell of Pneumocystis carinii; a virus; or, a parasitic helminth; or an arthropod.

In preferred embodiments where the cell is a bacterial cell, the bacterial cell can be a Staphylococcus, Streptococcus, Enterococcus, Mycobacterium, Pseudomonas, Salmonella, Shigella, Escherichia, Erwinia, Klebsiella, Borrelia, Treponema, Campylobacter, Helicobacter, Bordetella, Neisseria, Legionella, Leptospira, Serpulina, Mycoplasma, Bacteroides, Klebsiella, Yersinia, Chlamydia, Vibrio, Actinobacillus, Porphyria, Hemophilus, Pasteurella, Peptostreptococcus, Listeria, Propionibacterium, Mycobacterium, Corynebacterium or Dermatophilus cell.

In preferred embodiments where the cell is a fungal cell, the cell can be a Candida or an Aspergillus cell.

In preferred embodiments, the organism is Pneumocystis carinii.

In preferred embodiments where the target organism is a protozoan cell, the cell is an Entamoeba, a Toxoplasma, a Giardia, a Leishmania, a Crytosporidium, or a Schistosoma.

In preferred embodiments where the target organism is a virus, the virus is an HIV, an HTLV, a hepatitis virus, an influenza virus, a rhinovirus, a papilloma virus, a measles virus, a Herpes virus, a rotavirus, a parvovirus, a psittacosis virus, or an Ebola virus.

In preferred embodiments where the target organism is an arthropod, the arthropod is a parasitic mite.

In preferred embodiments where the target organism is a helminth, the helminth is a nematode or a trematode.

In preferred embodiments the target organism is an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis.

In another aspect, the invention features a conjugate molecule which includes a photosensitizer coupled to a non-pair member (NPM) targeting moiety and a pharmaceutically acceptable carrier.

In another aspect, the invention features, a conjugate molecule which includes a photosensitizer coupled to a targeting moiety which includes a non-pair member (NPM) polypeptide moiety having affinity for an oral bacterial species.

In embodiments in which the targeting moiety includes a polypeptide, the targeting moiety can be a linear, branched, or cyclic polypeptide.

In particularly preferred embodiments the targeting moiety includes a polylysine molecule. The polylysine can be between 6 and 15, 12 and 18, 18 and 30, 20 and 40, 30 and 60, 80 and 120, 150 and 300, 300 and 600, 800 and 1,200, or 2,000 and 3,000 residues in length.

In preferred embodiments the targeting moiety includes a polypeptide, e.g., a polyamino acid, which has been chemically modified to alter its charge, e.g., the charge of side chains of one or more amino acid residues of the polyamino acid. For example, one or more, or approximately 10, 25, 50, 75, 90 or 100% of the charged side cains can be modified. By modified is meant that a negative side chain, e.g., a glutamic acid, or an aspartic acid, side chain is made positive or neutral in charge, a positively charged side chain, e.g., the side chain of lysine, arginine, or ornithine is made negative or neutral in charge. By way of example, one or more of the side chains of polylysine can be made neutral or negative in charge.

In preferred embodiments: the photosensitizer produces singlet oxygen upon absorption of electromagnetic irradiation at the proper energy level and wavelength; the photosensitizer includes a porphyrin or porphyrin derivative; the photosensitizer includes chlorin e6 or a chlorin derivative.

In preferred embodiments the conjugate further includes a backbone member. In such embodiments the backbone is coupled both to a photosensitizer and to a targeting moiety. The backbone can itself also be a targeting moiety, e.g. polylysine.

In preferred embodiments the conjugate includes chlorin e6 conjugated to polylysine, e.g., 1 or 2 to 20 chlorin e6 molecules conjugated to a polylysine between about 1,000 and 3,000 in molecular weight.

In preferred embodiments the conjugate includes chlorin e6 conjugated to a histatin polypeptide, or an active fragment or analog thereof, e.g., 1 or 2 to 4 chlorin e6 molecules conjugated to a histatin-5 polypeptide.

In preferred embodiments the conjugate includes chlorin e6 and a histatin polypeptide, or an active fragment or analog thereof, conjugated to a polylysine backbone, e.g., either from one to 4 polylysine chains (MW 1,000 to 3,000 daltons, each containing from 1 or 2 to 20 chlorin e6 molecules) joined to one histatin-5 polypeptide, or from one to 4 histatin-5 polypeptides joined to a polylysine chain (MW 1,000 to 3,000 and containing 1 or 2 to 16 chlorin e6 molecules.

In preferred embodiments the target organism is an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In preferred embodiments, the targeting moiety includes a salivary polypeptide, or an active fragment or analog thereof. Examples of salivary polypeptides are the histatins, e.g., histatin-1 through -8, or more preferably, histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In another aspect, the invention features, a method of treating a subject, for a disorder characterized by the presence of an unwanted organism. The method includes:

administering to the subject, a conjugate which includes a photosensitizer coupled to a NPM targeting moiety, e.g., a conjugate described herein;

irradiating the subject with energy of a wavelength appropriate to produce a cytotoxic effect by the photosensitizer;

thereby treating the subject, for the disorder characterized by the presence of an unwanted organism.

In preferred embodiments, the unwanted organism, by way of example, can be: a microorganism, e.g., a bacterial cell, a fungal cell, a protozoan cell, a cell of Pneumocystis carinii; a virus; or, a parasitic helminth; or an arthropod.

In preferred embodiments where the unwanted organism is a bacterial cell, the bacterial cell can be a Staphylococcus, Streptococcus, Enterococcus, Mycobacterium, Pseudomonas, Salmonella, Shigella, Escherichia, Erwinia, Klebsiella, Borrelia, Treponema, Campylobacter, Helicobacter, Bordetella, Neisseria, Legionella, Leptospira, Serpulina, Mycoplasma, Bacteroides, Klebsiella, Yersinia, Chlamydia, Vibrio, Actinobacillus, Porphyria, Hemophilus, Pasteurella, Peptostreptococcus, Listeria, Propionibacterium, Mycobacterium, Corynebacterium or Dermatophilus cell. In more preferred embodiments the bacterial cell can be a Porphyromonas (Bacteroides) gingivalis; Bacteroides species including B. gingivalis (now known as Porphyromonas gingivalis), Eikenella corrodens, Fusobacterium nucleatum, Wolinella recta, Eubacterium species, Prevotella (Bacteroides) intermedia, Bacteroides forsythus, Capnocytophaga species, Actinobacillus actinomycetamcomitans, and Streptococcus mutans.

In preferred embodiments where the bacterial cell is a Treponema cell, the disorder is trenchmouth, yaws, or pinta. In other embodiments the disorder is impetigo or cystic acne.

In preferred embodiments where the unwanted organism is a fungal cell, the cell can be a Candida or an Aspergillus cell. In preferred embodiments, the organism is Pneumocystis carinii.

In preferred embodiments where the unwanted organism is a protozoan cell, the cell is an Entamoeba, a Toxoplasma, a Giardia, a Leishmania, a Crytosporidium, or a Schistosoma.

In preferred embodiments where the unwanted organism is a virus, the virus is an HIV, an HTLV, a hepatitis virus, an influenza virus, a rhinovirus, a papilloma virus, a measles virus, a Herpes virus, a rotavirus, a parvovirus, a psittacosis virus, or an Ebola virus.

In preferred embodiments where the target organism is an arthropod, the arthropod is a parasitic mite.

In preferred embodiments where the target organism is a helminth, the helminth is a nematode or a trematode. In preferred embodiments where the helminth is a nematode, the nematode is found in a subject with filariasis.

In preferred embodiments the target organism is an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In another aspect, the invention features, a method of treating a subject, for a disorder of the oral cavity characterized by the presence of an unwanted organism. The method includes:

administering to the subject, a conjugate which includes a photosensitizer coupled to a NPM targeting moiety, e.g., a conjugate described herein;

irradiating the subject with energy of a wavelength appropriate to produce a cytotaxic effect by the photosensitizer;

thereby treating the subject, for the disorder characterized by the presence of an unwanted organism.

In preferred embodiments the method includes topically administering the conjugate to an area of the subject which is infected with the unwanted organisms. The conjugate can be topically administered e.g., generally to the surfaces of the oral cavity, to the gums, to the periodontal tissue, to the periodontal pocket, to areas characterized by inflammation, to lesions, to fissures or imperfections in a tooth or gum, to dental carries, to cuts or incisions, e.g., those made in the course of dental or other medical care, or to wounds. In other embodiments the method includes systemic administration, e.g., by ingestion or injection. In other embodiments the method includes subcutaneous delivery, e.g., subcutaneous injection. In other embodiments the method includes local injection at or near the site of infection with the unwanted organism.

In preferred embodiments the radiation: is laser irradiation; or is delivered with a fiber optic devise.

In preferred embodiments the subject is suffering from: a disorder of the oral cavity which is characterized by the presence of an unwanted organism, e.g., a microbial organism, e.g., an unwanted bacterium, fungus, virus, or protozoan. The disorder can be one in which any of the teeth, gums, e.g., the periodontal tissue, tongue, tonsils, uvula, lining of the oral cavity, or parotid glands, are infected by the organism or otherwise affected by the disorder.

In preferred embodiments the disorder is an infectious oral disease.

In preferred embodiments the subject is suffering from: a periodontal disease, e.g., periodontitis or periodontosis; receding gums; acute ulcerative gingivitis; chronic gingivitis; periodontal abscess; early onset (juvenile) periodontitis; gingivitis of pregnancy; pericoronitis; infective stomatitis; cancrum oris; suppurative paratitis; acute or chronic osteomyelitis of the mandibles or maxilla; pulpitis or periapical infections.

In preferred embodiments the subject is suffering from an oral fungal infection, e.g., an actinomycosis, histoplasmosis, phycomycosis, aspergillosis, cryptococcosis, sporotrichosis, blastomycosis, or paracoccidioidomycosis infection.

In other preferred embodiments, the subject is suffering from an oral yeast infection, e.g., including a Candida infection of the oral cavity, e.g., candidosis (candidiasis), thrush, chronic candidosis and candidal (candididal) leukoplakia, or from a viral infection including primary herpetic stomatitis, or herpes labialis.

In preferred embodiments the subject, in addition to suffering from a disorder of the oral cavity, is suffering from an immune disorder, e.g., an acquired or inherited immune disorder. In particularly preferred embodiments the subject is suffering from AIDS or is HIV positive.

In preferred embodiments the unwanted organism is: an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis; Bacteroides species including B. gingivalis (now known as Porphyromonas gingivalis), Eikenella corrodens, Fusobacterium nucleatum, Wolinella recta, Eubacterium species, Prevotella (Bacteroides) intermedia, Bacteroides forsythus, Capnocytophaga species, Actinobacillus actinomycetamcomitans, and Streptococcus mutans.

In preferred embodiments, the targeting moiety of the conjugate includes a salivary polypeptide, or an active fragment or analog thereof. Examples of salivary polypeptides are the histatins, e.g., histatin-1 through -8, or more preferably, histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In particularly preferred embodiments the targeting moiety includes a polylysine molecule.

In preferred embodiments the targeting moiety includes a polypeptide, e.g., a polyamino acid, which has been chemically modified to alter its charge, e.g., the charge of side chains of one or more amino acid residues of the polyamino acid. For example, one or more, or approximately 10, 25, 50, 75, 90 or 100% of the charged side chains can be modified. By modified is meant that a negative side chain, e.g., a glutamic acid, or an aspartic acid, side chain is made positive or neutral in charge, a positively charged side chain, e.g., the side chain of lysine, arginine, or ornithine is made negative or neutral in charge. By way of example, one or more of the side chains of polylysine can be made neutral or negative in charge.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In preferred embodiments: the photosensitizer produces singlet oxygen upon absorption of electromagnetic irradiation at the proper energy level and wavelength; the photosensitizer includes a porphyrin or porphyrin derivative; the photosensitizer includes chlorin e6 or a chlorin derivative.

In another aspect, the invention features a method of treating a subject for a periodontal disorder characterized by the presence of an unwanted organism. The method includes:

administering to the subject, a conjugate which includes a photosensitizer coupled to a NPM targeting moiety, e.g., a conjugate described herein;

irradiating periodontal tissue of the subject with energy of a wavelength appropriate to produce a cytotaxic effect by the photosensitizer;

thereby treating the subject, for the periodontal disorder.

In preferred embodiments the method includes topically administering the conjugate to an area of the subject which is infected with the unwanted organisms. The conjugate can be topically administered to the gums, to the periodontal tissue, to the periodontal pocket, to areas characterized by inflammation, or lesions. In other embodiments the method includes systemic administration, e.g., by ingestion or injection. In other embodiments the method includes subcutaneous delivery, e.g., subcutaneous injection. In other embodiments the method includes local injection at or near the site of infection with the unwanted organism.

In preferred embodiments the subject is suffering from: periodontitis or periodontosis; receding gums; acute ulcerative gingivitis; chronic gingivitis; periodontal abscess; early onset (juvenile) periodontitis; gingivitis of pregnancy.

In preferred embodiments the subject, in addition to suffering from a periodontal disorder, is suffering from an immune disorder, e.g., an acquired or inherited immune disorder. In particularly preferred embodiments the subject is suffering from AIDS or is HIV positive.

In preferred embodiments the unwanted organism is: an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis; Bacteroides species including B. gingivalis (now known as Porphyromonas gingivalis), Eikenella corrodens, Fusobacterium nucleatum, Wolinella recta, Eubacterium species, Prevotella (Bacteroides) intermedia, Bacteroides forsythus, Capnocytophaga species, Actinobacillus actinomycetamcomitans, and Streptococcus mutans.

In preferred embodiments, the targeting moiety of the conjugate includes a salivary polypeptide, or an active fragment or analog thereof. Examples of salivary polypeptides are the histatins, e.g., histatin-1 through -8, or more preferably, histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In particularly preferred embodiments the targeting moiety includes a polylysine molecule.

In preferred embodiments the targeting moiety includes a polypeptide, e.g., a polyamino acid, which has been chemically modified to alter its charge, e.g., the charge of side chains of one or more amino acid residues of the polyamino acid. For example, one or more, or approximately 10, 25, 50, 75, 90 or 100% of the charged side chains can be modified. By modified is meant that a negative side chain, e.g., a glutamic acid, or an aspartic acid, side chain is made positive or neutral in charge, a positively charged side chain, e.g., the side chain of lysine, arginine, or ornithine is made negative or neutral in charge. By way of example, one or more of the side chains of polylysine can be made neutral or negative in charge.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In preferred embodiments: the photosensitizer produces singlet oxygen upon absorption of electromagnetic irradiation at the proper energy level and wavelength; the photosensitizer includes a porphyrin or porphyrin derivative; the photosensitizer includes chlorin e6 or a chlorin derivative.

In another aspect, the invention features, a method of treating a subject having an acquired immune disorder having an acquired immune disorder, for a disorder of the oral cavity characterized by the presence of an unwanted organism. In preferred embodiments the unwanted organism is other than an organism which is causative of the acquired immune disorder. The acquired immune disorder can be, e.g., AIDS, or an HIV infection. The method includes:

administering to the subject, a conjugate which includes a photosensitizer coupled to a NPM targeting moiety, e.g., a conjugate described herein;

irradiating the subject with energy of a wavelength appropriate to produce a cytotaxic effect by the photosensitizer;

thereby treating the subject, for the disorder characterized by the presence of an unwanted organism.

In preferred embodiments the method includes topically administering the conjugate to an area of the subject which is infected with the unwanted organisms. The conjugate can be topically administered e.g., generally to the surfaces of the oral cavity, to the gums, to the periodontal tissue, to the periodontal pocket, to areas characterized by inflammation, to lesions, to fissures or imperfections in a tooth or gum, to dental carries, to cuts or incisions, e.g., those made in the course of dental or other medical care, or to wounds. In other embodiments the method includes systemic administration, e.g., by ingestion or injection. In other embodiments the method includes subcutaneous delivery, e.g., subcutaneous injection. In other embodiments the method includes local injection at or near the site of infection with the unwanted organism.

In preferred embodiments the radiation: is laser irradiation; or is delivered with a fiber optic devise.

In preferred embodiments the unwanted organism is, e.g., a microbial organism, e.g., an unwanted bacterium, fungus, virus, or protozoan. The disorder can be one in which any of the teeth, gums, e.g., the periodontal tissue, tongue, tonsils, uvula, lining of the oral cavity, parotid glands, are infected by the organism or otherwise affected by the disorder.

In preferred embodiments the disorder is an infectious oral disease.

In preferred embodiments the subject is suffering from: a periodontal disease, e.g., periodontitis or periodontosis; receding gums; acute ulcerative gingivitis; chronic gingivitis; periodontal abscess; early onset (juvenile) periodontitis; gingivitis of pregnancy; periocoronities; infective stomatitis; cancrum oris; suppurative paratitis; acute or chronic osteomyelitis of the mandibles or maxilla; pulpitis or perioapical infections.

In preferred embodiments the subject is suffering from an oral fungal infection, e.g., an actinomycosis, histoplasmosis, phycomycosis, aspergillosis, cryptococcosis, sporotrichosis, blastombycosis, or paracoccidioidomycosis infection. In other preferred embodiments, the subject is suffering from an oral yeast infection, e.g., including a Candida infection of the oral cavity, e.g., candidosis (candidiasis), thrush, chronic candidosis and candidal (candididal) leukoplakia, or from a viral infection including primary herpetic stomatitis, or herpes labialis.

In preferred embodiments the unwanted organism is: an oral bacterial species, e.g., Porphyromonas (Bacteroides) gingivalis; Bacteroides species including B. gingivalis (now known as Porphyromonas gingivalis), Eikenella corrodens, Fusobacterium nucleatum, Wolinella recta, Eubacterium species, Prevotella (Bacteroides) intermedia, Bacteroides forsythus, Capnocytophaga species, Actinobacillus actinomycetamcomitans, and Streptococcus mutans.

In preferred embodiments, the targeting moiety of the conjugate includes a salivary polypeptide, or an active fragment or analog thereof. Examples of salivary polypeptides are the histatins, e.g., histatin-1 through -8, or more preferably, histatin-1, -3, or -5. In preferred embodiments the targeting moiety includes histatin-5 residues 13-24, or corresponding residues from other histatins. In preferred embodiments the targeting moiety includes a histatin molecule which has been engineered to include an internal duplication.

In particularly preferred embodiments the targeting moiety includes a polylysine molecule.

In preferred embodiments the targeting moiety includes a polypeptide, e.g., a polyamino acid, which has been chemically modified to alter its charge, e.g., the charge of side chains of one or more amino acid residues of the polyamino acid. For example, one or more, or approximately 10, 25, 50, 75, 90 or 100% of the charged side chains can be modified. By modified is meant that a negative side chain, e.g., a glutamic acid, or an aspartic acid, side chain is made positive or neutral in charge, a positively charged side chain, e.g., the side chain of lysine, arginine, or ornithine is made negative or neutral in charge. By way of example, one or more of the side chains of polylysine can be made neutral or negative in charge.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In preferred embodiments: the photosensitizer produces singlet oxygen upon absorption of electromagnetic irradiation at the proper energy level and wavelength; the photosensitizer includes a porphyrin or porphyrin derivative; the photosensitizer includes chlorin e6 or a chlorin derivative.

In another embodiment, the invention includes a method for making conjugate molecules, the method comprising:

supplying a backbone, e.g., a polypeptide backbone;

coupling, e.g., covalently coupling, a photosensitizer to the backbone;

coupling, e.g., covalently coupling, a targeting moiety, e.g., a targeting moiety described herein, to the backbone.

In preferred embodiments, the coupling reactions involve an activated ester moiety of a photosensitizer. In more preferred embodiments, an amino group on the backbone reacts as a nucleophile, displacing the leaving group from the photosensitizer active ester. In preferred embodiments, the targeting moiety is coupled to the backbone with a coupling agent.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

In another aspect, the invention features, a kit for elimination of an unwanted organism. The kit includes a photosensitizer coupled to a targeting moiety and instructions for use.

In preferred embodiments, the conjugate does not include, e.g., it is not coupled, e.g., covalently or non-covalently coupled to: a PM; an antibody; an enzyme; a hormone; a receptor on a cell surface; or the ligand for a receptor on a cell surface.

Photodynamic therapy involves the use of a light activatable compound, or photosensitizer, together with light of the correct wavelength, to produce a cytotoxic effect. In order to increase the specificity of the photosensitizer for its target, the photosensitizer may be bound to a targeting moiety. Methods and conjugates of the invention features the use of NPM-targeted photosensitizers. NPM's can deliver photosensitizer to a target in an efficient and cost effective manner. Compositions of the invention are advantageous in that (i) they do not need to be internalized to kill bacteria, since illumination generates toxic oxygen species which can diffuse through the bacterial cell wall, (ii) the generation of toxic oxygen species can have a local effect in stimulating the host immune response which can assist in eradicating bacteria and in promoting healing of the wound, (iii) they produce a cytotoxic response only in the area subject to illumination.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those herein can be used in the practice or testing of the present invention, the preferred methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

DETAILED DESCRIPTION OF THE INVENTION

Photosensitizers

A photosensitizer is a substance which, upon irradiation with electromagnetic energy of the appropriate wavelength, usually light of the appropriate wavelength, produces a cytotoxic effect.

Many photosensitizers produce singlet oxygen. Upon electromagnetic irradiation at the proper energy level and wavelength, such a photosensitizer molecule is converted to an energized form. The energized form can react with atmospheric O.sub.2, such that upon decay of the photosensitizer to the unenergized state, singlet oxygen is produced. Singlet oxygen is highly reactive, and is toxic to a proximal target organism.

The life-time of its triplet energized state should be of sufficient duration (e.g., several microseconds) to permit interaction with neighboring molecules to produce cytotoxic species.

A photosensitizer composition should efficiently absorb electromagnetic energy of the appropriate wavelength with high quantum yield to efficiently generate the energized form of the photosensitizer. Toxicity to the target organism should increase substantially, preferably 10-fold, 100-fold, or even more preferably 1,000-fold, upon irradiation. A photosensitizer should exhibit low background toxicity, i.e., low toxicity in the absence of irradiation with energy of the appropriate wavelength.

Other preferred properties of a photosensitizer include high solubility and stability in appropriate solvents. For example, a photosensitizer should be soluble under conditions used to couple it to the targeting moiety or backbone. Desired solubility properties will differ with the conditions chosen for the reaction but solubility in DMSO, water, ethanol, or a mixture of water and DMSO or in ethanol, such as DMSO:H.sub.2O, or in ethanol:water 5%, 10% or 15% can be useful. Solubility is preferably 50 .mu.g/ml, 100 .mu.g/ml, 500 .mu.g/ml, 1 mg/ml or 10 mg/ml in an aqueous solvent or ethanol:water solvent.

When conjugated to a targeting moiety, the resulting photosensitizer:targeting moiety conjugate should be soluble under physiological conditions, in aqueous solvents containing appropriate carriers and excipients, or other delivery systems such as in liposomes. The molecules of the invention may be delivered as free photosensitizer:targeting moiety compositions in solution, and may be delivered also in various formulations including, but not limited to, liposome, peptide/polymer-bound, or detergent-containing formulations.

The compositions of the invention should be stable during the course of at least a single round of treatment by continuous or pulsed irradiation, during which each molecule of the composition would preferably be repeatedly excited to the energized state, undergoing multiple rounds of generation of singlet oxygen. Preferable stability of a photosensitizer conjugate molecule is survival of 10%, 50%, 90%, 95%, or 99% of molecules in active form for 1 hour, for 30 min, 15 min or for at least 1 min at 37.degree. C., under physiological conditions.

Photosensitizers include, but are not limited to, hematoporphyrins, such as hematoporphyrin HCl and hematoporphyrin esters (Dobson, J. and M. Wilson, Archs. Oral Biol. 37:883-887); dihematophorphyrin ester (Wilson, M. et al., 1993, Oral Microbiol. Immuno. 8:182-187); hematoporphyrin IX (Russell et al., 1991, Can J. App. Spectros. 36:103-107, available from Porphyrin Products, Logan, Utah) and its derivatives; 3,1-meso tetrakis (o-propionamidophenyl) porphryrin; hydroporphyrins such as chlorin, herein, and bacteriochlorin of the tetra (hydroxyphenyl) porphyrin series, and synthetic diporphyrins and dichlorins; o-substituted tetraphenyl porphyrins (picket fence porphyrins); chlorin e6 monoethylendiamine monamide (CMA Goff, B. A. et al., 1994, 70:474-480, available from Porphyrin Products, Logan, Utah); mono-1-aspartyl derivative of chlorin e6, and mono- and di-aspartyl derivatives of chlorin e6; the hematoporphyrin mixture Photofrin II (Quardra Logic Technologies, Inc., Vancouver, BC, Canada); benzophorphyrin derivatives (BPD), including benzoporphyrin monoacid Ring A (BPD-MA), tetracyanoethylene adducts, dimethyl acetylene dicarboxylate adducts, Diels-Adler adducts, and monoacid ring "a" derivatives; a naphthalocyanine (Biolo, R., 1994, Photochem. and Photobio 5959:362-365); a Zn(II)-phthalocyanine (Shopora, M. et al., 1995, Lasers in Medical Science 10:43-46); toluidine blue O (Wilson, M. et al., 1993, Lasers in Medical Sci. 8:69-73); aluminum sulfonated and disulfonated phthalocyanine ibid.; and phthalocyanines without metal substituents, and with varying other substituents; a tetrasulfated derivative; sulfonated aluminum naphthalocyanines; methylene blue (ibid); nile blue; crystal violet; azure .beta. chloride; and rose bengal (Wilson, M., 1994, Intl. Dent. J. 44:187-189). Numerous photosensitizer entities are disclosed in Wilson, M. et al., 1992, Curr. Micro. 25:77-81, and in Okamoto, H. et al., 1992, Lasers in Surg. Med. 12:450-485.

Other potential photosensitizer compositions include but are not limited to, pheophorbides such as pyropheophorbide compounds, anthracenediones; anthrapyrazoles; aminoanthraquinone; phenoxazine dyes; phenothiazine derivatives; chalcogenapyrylium dyes including cationic selena- and tellura-pyrylium derivatives; verdins; purpurins including tin and zinc derivatives of octaethylpurpurin and etiopurpurin; benzonaphthoporphyrazines; cationic imminium salts; and tetracyclines.

The suitability of a photosensitizer for use in a conjugate can be determined by methods described herein or by methods known to those skilled in the art.

The efficiency with which a photosensitizer oxidizes a target molecule is a measure of the usefulness. The efficiency of the oxidation of a target molecule by a photosensitizer can be determined in vitro. Examples of substrates include 4-nitroso-N,N-dimethylaniline (RNO; Hasan, T. et al., 1987, Proc. AACR 28:395 Abstr. 1,568), and tryptophan or histidine (Lambert, C. R. et al., 1986, Photochem. Photobiol. 44:595-601). In these assays, ability of a candidate photosensitizer to "bleach" the substrate can be monitored spectroscopically. The advantage of a chemical assay is that a large number of putative photosensitizer compositions can be simultaneously screened. Parameters which can be varied include photosensitizer concentration, substrate concentration, optimal intensity of irradiation, and optimal wavelength of irradiation. High through-put technologies including plastic multi-well dishes, automated multi-pipetters, and on-line spectrophotometric plate readers can be used. Undesirable candidates, e.g., compositions having high backgrounds under unirradiated conditions, inefficient energy capture or reactive potential, can be identified and eliminated.

In vivo assays with cells of one or more model target organisms can be used to evaluate a photosensitizer for cytotoxicity of its background and activated forms. The efficiency of killing of the organism in the presence of the irradiated and unirradiated photosensitizer can be measured and compared to survival of the untreated control cell sample. This assay can be automated. The use of counts of colony forming units (CFU) or cell growth may require incubation of the samples that have been applied to a nutrient medium, with a concomitant lag of the appropriate growth period to allow for colony formation.

Survival of cells of the model target organism can alternatively be monitored by assay of a biochemical process, for example, assay of DNA synthesis. In this approach the effectiveness of a photosensitizer candidate can be measured by its effect on samples of cells of the model organism, which are also exposed to a labeled DNA precursor such as tritiated thymidine. Cells are then collected, washed to remove unincorporated precursor, and monitored for uptake of the precursor and incorporation into acid-insoluble precipitate, which is a measure of quantity of DNA synthesis. In this assay, which can also be automated as described above, quantitative evaluation of the effects of presence of irradiated photosensitizer compositions can be readily evaluated and quantitated. In control unirradiated cells and in untreated cells, DNA synthesis increases logarithmically as a function of cell growth. A positive result indicating presence of a putative successful novel photosensitizer, is turn-off of DNA synthesis in cells that have been irradiated in the presence of that photosensitizer.

Suitable model target organisms are: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus mutans. A suitable positive control for photosensitizer activity is toluidine blue O.

If large numbers of candidates are to be screened it may be desirable to use a two-stage screen, wherein the first stage is an in vitro screen and wherein the second stage uses cells.

Irradiation

Irradiation of the appropriate wavelength for a given compound may be administered by a variety of methods. These methods include but are not limited to the administration of laser, nonlaser, or broad band light. Irradiation can be produced by extracorporeal or intraarticular generation of light of the appropriate wavelength. Light used in the invention may be administered using any device capable of delivering the requisite power of light including, but not limited to, fiber optic instruments, arthroscopic instruments, or instruments which provide transillumination. Delivery of light to the oral cavity can be accomplished with flexible fiber optics which are inserted into the periodontal pocket, or by transgingival illumination (average thickness of gingiva is 5-7 mm). The source of the light needed to inactivate the bacteria can be an inexpensive diode laser or a non-coherent light source.

Coupling Technologies

The term "coupling agent" as used herein, refers to a reagent capable of coupling a photosensitizer to a targeting moiety, or a photosensitizer or a targeting moiety to a "backbone" or "bridge" moiety. Any bond which is capable of linking the components such that they are stable under physiological conditions for the time needed for administration and treatment is suitable, but covalent linkages are preferred. The link between two components may be direct, e.g., where a photosensitizer is linked directly to a targeting moiety, or indirect, e.g., where a photosensitizer is linked to an intermediate, e.g., linked to a backbone, and that intermediate being linked to the targeting moiety. A coupling agent should function under conditions of temperature, pH, salt, solvent system, and other reactants that substantially retain the chemical stability of the photosensitizer, the backbone (if present), and the targeting moiety.

A coupling agent can link components without the addition to the linked components of elements of the coupling agent. Other coupling agents result in the addition of elements of the coupling agent to the linked components. For example, coupling agents can be cross-linking agents that are homo- or hetero-bifunctional, and wherein one or more atomic components of the agent can be retained in the composition. A coupling agent that is not a cross-linking agent can be removed entirely during the coupling reaction, so that the molecular product can be composed entirely of the photosensitizer, the targeting moiety, and a backbone moiety (if present).

Many coupling agents react with an amine and a carboxylate, to form an amide, or an alcohol and a carboxylate to form an ester. Coupling agents are known in the art, see, e.g., M. Bodansky, "Principles of Peptide Synthesis", 2nd ed., referenced herein, and T. Greene and P. Wuts, "Protective Groups in Organic Synthesis," 2nd Ed, 1991, John Wiley, N.Y. Coupling agents should link component moieties stably, but such that there is only minimal or no denaturation or deactivation of the photosensitizer or the targeting moiety.

The photosensitizer conjugates of the invention can be prepared by coupling the photosensitizer to targeting moieties using methods described in the following Examples, or by methods known in the art. A variety of coupling agents, including cross-linking agents, can be used for covalent conjugation. Examples of cross-linking agents include N,N'-dicyclohexylcarbodiimide (DCC; Pierce), N-succinimidyl-S-acetyl-thioacetate (SATA), N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), ortho-phenylenedimaleimide (o-PDM), and sulfosuccinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (sulfo-SMCC). See, e.g., Karpovsky et al. J. Exp. Med. 160:1686, 1984; and Liu, M A et al., Proc. Natl. Acad. Sci. USA 82:8648, 1985. Other methods include those described by Paulus, Behring Ins. Mitt., No. 78, 118-132, 1985; Brennan et al. Science 229:81-83, 1985, and Glennie et al., J. Immunol., 139: 2367-2375, 1987. A large number of coupling agents for peptides and proteins, along with buffers, solvents, and methods of use, are described in the Pierce Chemical Co. catalog, pages T-155-T-200, 1994 (3747 N. Meridian Rd., Rockford Ill., 61105, U.S.A.; Pierce Europe B.V., P.O. Box 1512, 3260 BA Oud Beijerland, The Netherlands), which catalog is hereby incorporated by reference.

DCC is a useful coupling agent (Pierce #20320; Rockland, Ill.). It promotes coupling of the alcohol NHS to chlorin e6 in DMSO (Pierce #20684), forming an activated ester which can be cross-linked to polylysine. DCC (N,N'-dicyclohexylcarbodiimide) is a carboxy-reactive cross-linker commonly used as a coupling agent in peptide synthesis, and has a molecular weight of 206.32. Another useful cross-linking agent is SPDP (Pierce #21557), a heterobifunctional cross-linker for use with primary amines and sulfhydryl groups. SPDP has a molecular weight of 312.4, a spacer arm length of 6.8 angstroms, is reactive to NHS-esters and pyridyldithiol groups, and produces cleavable cross-linking such that, upon further reaction, the agent is eliminated so the photosensitizer can be linked directly to a backbone or targeting moiety. Other useful conjugating agents are SATA (Pierce #26102) for introduction of blocked SH groups for two-step cross-linking, which is deblocked with hydroxylamine-HCl (Pierce #26103), and sulfo-SMCC (Pierce #22322), reactive towards amines and sulfhydryls. Other cross-linking and coupling agents are also available from Pierce Chemical Co. (Rockford, Ill.). Additional compounds and processes, particularly those involving a Schiff base as an intermediate, for conjugation of proteins to other proteins or to other compositions, for example to reporter groups or to chelators for metal ion labeling of a protein, are disclosed in EPO 243,929 A2 (published Nov. 4, 1987).

Photosensitizers which contain carboxyl groups can be joined to lysine .epsilon.-amino groups in the target polypeptides either by preformed reactive esters (such as N-hydroxy succinimide ester) or esters conjugated in situ by a carbodiimide-mediated reaction. The same applies to photosensitizers which contain sulfonic acid groups, which can be transformed to sulfonyl chlorides which react with amino groups. Photosensitizers which have carboxyl groups can be joined to amino groups on the polypeptide by an in situ carbodiimide method. Photosensitizers can also be attached to hydroxyl groups, of serine or threonine residues or to sulfhydryl groups of cysteine residues.

Methods of joining components of a conjugate, e.g., coupling polyamino acid chains bearing photosensitizers to antibacterial polypeptides, can use heterobifunctional cross linking reagents. These agents bind a functional group in one chain and to a different functional group in the second chain. These functional groups typically are amino, carboxyl, sulfhydryl, and aldehyde. There are many permutations of appropriate moieties which will react with these groups and with differently formulated structures, to conjugate them together. See the Pierce Catalog, and Merrifield, R. B., et al. Ciba Found Symp. 186:5-20, 1994.

The production and purification of photosensitizer:targeting moiety conjugates can be practiced by methods known in the art. Yield from coupling reactions can be assessed by spectroscopy of product eluting from a chromatographic fractionation in the final step of purification. The presence of uncoupled photosensitizer and reaction products containing the photosensitizer can be followed by the physical property that the photosensitizer moiety absorbs light at a characteristic wavelength and extinction coefficient, so incorporation into products can be monitored by absorbance at that wavelength or a similar wavelength. Coupling of one or more photosensitizer molecules to a targeting moiety or to a backbone shifts the peak of absorbance in the elution profile in fractions eluted using sizing gel chromatography, e.g., with the appropriate choice of Sephadex G50, G100, or G200 or other such matrices (Pharmacia-Biotech, Piscataway N.J.). Choice of appropriate sizing gel, for example Sephadex gel, can be determined by that gel in which the photosensitizer elutes in a fraction beyond the excluded volume of material too large to interact with the bead, i.e., the uncoupled starting photosensitizer composition interacts to some extent with the fractionation bead and is concomitantly retarded to some extent. The correct useful gel can be predicted be predicted from the molecular weight of the uncoupled photosensitizer. The successful reaction products of photosensitizer compositions coupled to additional moieties generally have characteristic higher molecular weights, causing them to interact with the chromatographic bead to a lesser extent, and thus appear in fractions eluting earlier than fractions containing the uncoupled photosensitizer substrate. Unreacted photosensitizer substrate generally appears in fractions characteristic of the starting material, and the yield from each reaction can thus be assessed both from size of the peak of larger molecular weight material, and the decrease in the peak of characteristic starting material. The area under the peak of the product fractions is converted to the size of the yield using the molar extinction coefficient.

The product can be analyzed using NMR, integrating areas of appropriate product peaks, to determine relative yields with different coupling agents. A red shift in absorption of a photosensitizer of several nm has often been observed following coupling to a polyamino acid. Coupling to a larger moiety such as a protein might produces a comparable shift, as coupling to an antibody resulted in a shift of about 3-5 nm in that direction compared to absorption of the free photosensitizer. Relevant absorption maxima and extinction coefficients in 0.1M NaOH/1% SDS are, for chlorin e6, 400 nm and 150,000 M-.sup.-1, cm.sup.-1, and for benzoporphyrin derivative, 430 nm and 61,000 M.sup.-1, cm.sup.-1.

Backbone Moieties

Photosensitizer:targeting moiety conjugates of the invention include those in which a photosensitizer is coupled directly to a targeting moiety, such as a histatin. Other photosensitizer:targeting moiety conjugates of the invention include a "backbone" or "bridge" moiety, such as a polyamino acid, which backbone is coupled both to a photosensitizer and to a targeting moiety. The backbone can itself be a targeting moiety, e.g. polylysine (see Example 4 and FIGS. 5 and 6).

Inclusion of a backbone in a conjugate with a photosensitizer moiety and a targeting moiety can provide a number of advantages, including the provision of greater stoichiometric ranges of photosensitizer and targeting moieties coupled per backbone. If the backbone possesses intrinsic affinity for a target organism, the affinity of the composition can be enhanced by coupling to the backbone. The specific range of organisms that can be targeted with one composition can be expanded by coupling two or more different targeting moieties to a single photosensitizer-backbone composition.

Peptides useful in the methods and compounds of the invention for design and characterization of backbone moieties include poly-amino acids which can be homo- and hetero-polymers of L-, D-, racemic DL- or mixed L- and D-amino acid composition, and which can be of defined or random mixed composition and sequence. Examples of naturally-occurring peptides with mixed D and L amino acid residues include bacitracin and tyrocidin. These peptides may be modeled after particular natural peptides, and optimized by the technique of phage display and selection for enhanced binding to a chosen target, so that the selected peptide of highest affinity is characterized and then produced synthetically. Further modifications of functional groups can be introduced for purposes, for example, of increased solubility, decreased aggregation, and altered extent of hydrophobicity. Examples of nonpeptide backbones include nucleic acids and derivatives of nucleic acids such as DNA, RNA and peptide nucleic acids; polysaccharides and derivatives such as starch, pectin, chitins, celluloses and hemi-methylated celluloses; lipids such as triglyceride derivatives and cerebrosides; synthetic polymers such as polyethylene glycols (PEGs) and PEG star polymers; dextran derivatives, polyvinyl alcohols, N-(2-hydroxypropyl)-methacrylamide copolymers, poly (DL-glycolic acid-lactic acid); and compositions containing elements of any of these classes of compounds.

Modification of the Charge of Conjugates

The affinity of a conjugate for a target organism can be refined by modifying the charge of a component of the conjugate.

Conjugates such as poly-L-lysine chlorin e6 can be made in varying sizes and charges (cationic, neutral, and anionic), for example, free NH.sub.2 groups of the polylysine are capped with acetyl, succinyl, or other R groups to alter the charge of the final composition. Net charge of a conjugate of the present invention can be determined by isoelectric focusing (IEF). This technique uses applied voltage to generate a pH gradient in a non-sieving acrylamide or agarose gel by the use of a system of ampholytes (synthetic buffering components). When charged polypeptides are applied to the gel they will migrate either to higher pH or to lower pH regions of the gel according to the position at which they become non-charged and hence unable to move further. This position can be determined by reference to the positions of a series of known IEF marker proteins.

Due to the combination of polar charged groups on the polyaminoacid, and the hydrophobic attraction between the planar aromatic tetrapyrrole rings, these conjugates can adopt pH dependent conformations which can interact with bacterial cell walls. In addition, histatins and related polypeptides contain at least one lysine residue which by the application of two heterobifunctional reagents will lead to a covalent disulfide link between the histatin and the polylysine chlorin e6 molecules. The optimum composition, concentration and time of application of the photosensitizer to various pathogenic oral bacteria can be determined.

Targeting Moieties

Desirable characteristics for the targeting moieties include: specificity for one or more unwanted target organisms, affinity and avidity for such organisms, and stability with respect to conditions of coupling reactions and the physiology of the organ or tissue of use. Specificity need not be narrowly defined, e.g., it may be desirable for a targeting molecule to have affinity for a broad range of target organisms, such as all Gram negative bacteria.

The targeting moiety, when incorporated into a conjugate molecule of the invention, should be nontoxic to the cells of the subject.

Targeting moieties can be selected from the sequences of naturally occurring proteins and peptides, from variants of these peptides, and from biologically or chemically synthesized peptides. Naturally occurring peptides which have affinity for one or more target organism can provide sequences from which additional peptides with desired properties, e.g., increased affinity or specificity, can be synthesized individually or as members of a library of related peptides. Such peptides can be selected on the basis of affinity for the target organism.

Naturally occurring peptides with affinity for target organisms useful in methods and compounds of the invention, include salivary proteins, e.g., histatins, microbially-elaborated proteins, e.g., bacteriocins, peptides that bind and/or kill species that are closely related to the producing strains; and proteins produced by animal species such as defensins, which are produced by mammals, and the cecropins and magainins, produced by moths and amphibia, respectively.

Histatins, defensins, cecropins and magainins are examples of a class of polypeptides found widely in nature, which share the characteristics of small size (generally approximately 30 amino acid residues, and between 10 residues and 50 residues), broad specificity of anti-microbial activity, and low affinity for target organisms.

The use of histatins as a photosensitizer targeting moieties will allow targeting a photosensitizer to a bacterial cell while leaving the host tissue unharmed. Histatins are a family of histidine-rich cationic polypeptides which have bactericidal and candidacidal properties and are constituents of normal human saliva (Oppenheim, G. G. et al., J. Biol. chem. 263:7472-747, 1988). Their mechanism of action is thought to involve a combination of alpha-helical conformation and cationic charge leading them to insert between the polar head groups in the bacterial cell wall (Raj, P. A. et al., J. Biol. Chem. 269:9610-9619, 1994).

While histatins can be used usefully employed as oral bacteriocides, their action occurs over time periods of hours, leading to the problem of formulating delivery vehicles such as gels to keep the histatins in the region of infection. Photodynamic inactivation of oral bacteria, however, can require only brief application of the bacteria-targeted photosensitizer, such as by supplying in a mouthwash. Because bacteria are 50-100 times smaller than the average mammalian cell and the mechanism of photodynamic therapy is thought to involve the production of molecular species such as singlet oxygen which have very short diffusion distances in tissues (less than 50 nm for singlet oxygen), it can be seen that modest levels of sensitizer selectivity for bacteria may lead to high levels of selectivity in cytotoxicity. Low levels of PDT in humans and experimental animals have been shown to activate components of the host immune system such as macrophages and lymphocytes, and these activated host cells may play a part in destroying bacteria and helping the regeneration of tissue destroyed by disease.

Histatins-1, -3 and -5 each contain 7 residues of histidine, in a total polypeptide length of 38, 32 and 24 residues, respectively. Histatins have a number of activities, for example, an anti-fungal activity, for example, against Candida pathogens. (U.S. Pat. No. 5,486,503). Recombinant duplication of histatin-5 residues 13-24 gives a peptide with enhanced candidacidal activity (Zuo, F. et al., Gene 161:87-91, 1995). Histatin-5 is an inhibitor of the trypsin-like protease produced by the oral bacterial species Porphyromonas (Bacteroides) gingivalis, which protease is associated with tissue destruction of periodontal disease (Nishikata, M. et al., Biochem. Biophys. Res. Comm. 174:625-630, 1991). About 3,600 histatin-5 molecules bind P. gingivalis with a K.sub.d on the order of 10.sup.-6 M (Murakami, Y. et al., FEMS Microbiol. Letts. 82:253-256, 1991). Histatins-5 and -8 inhibit coaggregation of P. gingivalis and S. mitis (Murakami, Y. et al., Inf. Immun. 59:3284-3286, 1991), which may modulate the attachment of P. gingivalis to Gram positive bacteria previously bound to oral tissues.

Histatin-5 has bactericidal activity against at least the oral bacterial species P. gingivalis (Colon, J. O. et al., J. Dent. Res. 72 IADR Abstr.:322, Abstr. 1751) and Actinomyces viscosus, A. naeslundii, and A. odontolyticus (Kalpidis, C. D. et al., op. cit. 71:305, Abstr. 1595). The direct anti-microbial activity against the latter species appears to be without receptor activity for agglutination of Actinomyces cells. A synthetic peptide of histatin-5 is a potent inhibitor of P. (B) gingivalis hemagglutinin (Murakami, Y. et al., Archs. Oral. Biol. 35:775-777). The synthetic peptide is strongly cationic (containing 6 His, 4 Lys, and 3 Arg in 22 residues) and may function as the binding domain for P. gingivalis on epithelial cells, salivary pellicle, and Gram positive cells.

Histatins that have been chemically capped at the C- or N-terminus, and complexed with a metal, for example Ag, Cu, Zn or Sn, are suitable for a range of anti-microbial applications, such as antiplaque, anti-caries, anti-bad breath oral applications, deodorant applications, personal hygiene applications and so on (EPO Patent Application Ser. No. 721 774 A2).

Bacteriocins, which are proteins produced by bacteria and which kill other strains and species of bacteria (Jack, R. W. et al., Microbiol. Rev. 59:171-200, 1995) can be used as targeting moieties. An exemplary Gram positive bacteriocin is nisin, produced by Lactococcus lactis and accorded GRAS status (generally regarded as safe) by the Food and Drug Administration for application to food preservation.

The bacteriocins nisin, subtilin, epidermin, gallidermin, salivarin, and lacticin exemplify the "lantibiotic" class of Gram positive bacteriocin, which is defined as a bacteriocin in which one or more cysteine residues are linked to a dehydrated serine or threonine to form a thioether-linked residue known as lanthionine (Lan) or threo-.beta.-methyllanthionine (MeLan). These are post-translational modifications found in these anti-microbial peptides by the producing cell. Lantibiotics contain leader peptide sequences of 18-24 residues, which are cleaved to yield an active antimicrobial peptide of about 22-35 residues. Growth of the producing bacterial species, and preparation and purification of bacteriocins are performed by published procedures and techniques which can be carried out by one of skill in the art. For example, Yang, R. et al., Appl. and Env. Microbiol 58: 3355-3359, 1992, describe purification of bacteriocins from each of 4 genera of lactic acid bacteria, by optimizing absorption onto the producing cells, followed by use of low pH for selective elution of greatly enriched bacteriocin fractions. Mutant forms of each of the bacteriocins nisin, produced by Lactococcus lactis, and of subtilin, produced by Bacillus subtilis have more desirable properties than the parental wild-type forms (Liu, W. and N. Hansen, J. Biol. Chem. 267:25,078-25,085, 1992). Procedures for isolation of appropriate genes and for mutagenesis and selection of strains carrying desirable mutations are found in Maniatis, T. et al, 1982, Molecular Cloning: a Laboratory Manual , Cold Spring Harbor Press, Cold Spring Harbor, N.Y., and in the subsequent second edition, Sambrook, J. et al., 1989.

Anti-microbial peptides are produced by a variety of animals (see review by Saberwal, G. and R. Nagaraj, Biochim. Biophys. Act. 1197:109-131, 1994). An example is a peptide of the cecropin family produced by Cecropia moths. Several cecropins contain 37 residues, of which 6 are lysine. Cecropins are active against both Gram positive and Gram negative bacteria. Other insect produced peptides include apidaecin (from honeybees), andropin (from fruit flies), and cecropin family members from bumble bees, fruit flies, and other insects.

The defensins are produced by mammals, including humans, and are generally about 29-34 residues in length, and the magainins (about 23 residues) are produced by amphibia such as Xenopus laevis. Defensins from human (HNP-1, -2, -3 and 4), guinea pig (GPNP), rabbit (NP-1, -2, -3A, -3B, 4 and -5) and rat (NP-1, -2, -3 and -4) share a significant number of regions of homology. Defensins can have antimicrobial activity against Gram positive bacteria or Gram negative bacteria and fungi, with minimal inhibitory concentrations in the mM range. Rabbit NP-1 and NP-2 are more potent antibacterial agents than others in this family. Other mammalian anti-microbial peptides include murine cryptdin, bovine granulocyte bactenecin and indolicidin, and seminal-plasmin from bovine semen. Additional amphibial anti-microbials include PGLA, XPF, LPF, CPG, PGQ, bombinin from Bombina variegata, the bombinin-like peptides BLP-1, -2, -3 and -4 from B. orientalis, and brevinins from Rana esculenta. Invertebrates such as the horseshoe crab can be a source of anti-microbial peptides such as the tachyplesins (I, II and III) and the polyphemusins (I and II).

Peptides in these families of antimicrobial agents are generally cationic, and can have a broad antimicrobial spectrum, including both antibacterial and antifungal activities. The addition of positively charged residues can enhance antimicrobial specific activity several fold. The positive charges are thought to assist in the insertion of the peptides into the membranes of the susceptible organisms, in which context the peptide molecules can form pores and cause efflux of ions and other metabolites. Structural studies of the Moses sole fish neurotoxin 33 residue peptide pardaxin, for example, reveals that succinylated pardaxin inserts into erythrocyte and model membranes more slowly than unmodified pardaxin. (Shai, Y et al., J. Biol. Chem. 265: 20, 202-20, 209, 1990). The positively charged magainin molecule can disrupt both the metabolism of E. coli and the electric potential of the mitochondrion (Westerhoff, H. V., et al., Proc. Natl. Acad. Sci. 86:6597-6601, 1989).

Novel peptides, for example a cecropin-meriting hybrid, and synthetic D-enantiomers, have antimicrobial activity (Merrifield, R. B. et al., "Antimicrobial peptides," Ciba Foundation Symp. 186, John Wiley, Chichester, pp. 5-26, 1994). One such synthetic cecropin-meriting peptide is 5-fold more active against Mycobacterium smegmatis than rifampin.

Targeting moieties can be plant proteins with affinities for particular target organisms, for example, a member of the lectin protein family with affinity for polysaccharides.

Targeting moieties can be synthetic peptides, such as polylysine, polyarginine, polyomithine, and synthetic heteropolypeptides that comprise substantial proportions of such positively charged amino acid residues. Such peptides can be chemically synthesized or produced biologically in recombinant organisms, in which case the targeting moiety peptide can be produced as part of a larger protein, for example as the N-terminus residues, and cleaved from that larger protein. Polypeptides suitable as "backbone" and "bridge" moieties are also suitable as target moieties, if they have sufficient affinity for the target organism. Considerations described are thus appropriate to consideration of a targeting moieties. Targeting moieties can be synthesized and selected or enriched by the variety of methods described herein.

Targeting moieties need not be limited to peptide compositions, but can be lectins, polysaccharides, steroids, and metalloorganic compositions. Tageting moieties can be comprised of compositions that are composed both of amino acids and sugars, such as mucopolysaccharides. A useful targeting moiety can be partially lipid and partially peptide in nature, such as low density lipoprotein. Serum lipoproteins especially high density and low density lipoproteins (HDL and LDL) can bind to bacterial surface proteins (Emancipator, K. et al., Infect. Immun. 60:596-601, 1992). HDL and especially reconstituted HDL neutralizes bacterial lipopolysaccharide both in vitro and in vivo (Wurfel M M et al., J. Exp. Med. 181:1743-1754, 1995). Endogenous LDL can protect against the lethal effects of endotoxin and Gram negative infection (Netea, M., et al., J. Clin. Invest. 97:1366-1372, 1996). The appropriate binding features of the lipoproteins to bacterial surface components can be identified by methods of molecular biology known in the art, and the binding feature of lipoproteins can be used as the targeting moiety in photosensitizer compositions of the present invention.

Production and Screening of Peptide Targeting Moiety Candidates

The inventor has discovered that molecules, e.g., peptides, other than antibodies and members of a high affinity ligand pairs, can be used to target a photosensitizer to a target organism. The following methods can be used to modify or refine the targeting moieties disclosed herein or to discover new targeting moieties.

Once an example of a targeting moiety of reasonable affinity has been provided, one skilled in the art can alter the disclosed structure (of a polylysine polypeptide, for example), by producing fragments or analogs, and testing the newly produced structures for modification of affinity or specificity. Examples of methods which allow the production and testing of fragments and analogs are discussed below. These methods can be used to make fragments and analogs of a known naturally occurring polypeptide or protein which is a targeting moiety, e.g., a polypeptide such as histatin or low density lipoprotein, each of which has binding affinity for cells of one or more bacterial species.

Generation of Fragments

Fragments of a protein can be produced in several ways, e.g., recombinantly, by proteolytic digestion, or by chemical synthesis. Internal or terminal fragments of a polypeptide can be generated by removing one or more nucleotides from one end (for a terminal fragment) or both ends (for an internal fragment) of a nucleic acid which encodes the polypeptide. Expression of the mutagenized DNA produces polypeptide fragments. Digestion with "end-nibbling" processive exonucleases can thus generate DNA's which encode an array of fragments. DNA's which encode fragments of a protein can also be generated by random shearing, restriction digestion or a combination of the above-discussed methods.

Fragments can also be chemically synthesized using techniques known in the art such as conventional Merrifield solid phase f-Moc or t-Boc chemistry. For example, peptides of the present invention may be arbitrarily divided into fragments of desired length with no overlap of the fragments, or divided into overlapping fragments of a desired length.

Generation of Analogs: Production of Altered DNA and Peptide Sequences by Random Methods

Amino acid sequence variants of a protein can be prepared by random mutagenesis of DNA which encodes a protein or a particular domain or region of a protein. Useful methods include PCR mutagenesis and saturation mutagenesis. A library of random amino acid sequence variants can also be generated by the synthesis of a set of degenerate oligonucleotide sequences. (Methods for screening proteins in a library of variants are elsewhere herein.)

PCR Mutagenesis

In PCR mutagenesis, reduced Taq polymerase fidelity is used to introduce random mutations into a cloned fragment of DNA (Leung et al., 1989, Technique 1:11-15). This is a very powerful and relatively rapid method of introducing random mutations. The DNA region to be mutagenized is amplified using the polymerase chain reaction (PCR) under conditions that reduce the fidelity of DNA synthesis by Taq DNA polymerase, e.g., by using a dGTP/dATP ratio of five and adding Mn.sup.2+ to the PCR reaction. The pool of amplified DNA fragments are inserted into appropriate cloning vectors to provide random mutant libraries.

Saturation Mutagenesis

Saturation mutagenesis allows for the rapid introduction of a large number of single base substitutions into cloned DNA fragments (Mayers et al., 1985, Science 229:242). This technique includes generation of mutations, e.g., by chemical treatment or irradiation of single-stranded DNA in vitro, and synthesis of a complementary DNA strand. The mutation frequency can be modulated by modulating the severity of the treatment, and essentially all possible base substitutions can be obtained. Because this procedure does not involve a genetic selection for mutant fragments both neutral substitutions, as well as those that alter function, are obtained. The distribution of point mutations is not biased toward conserved sequence elements.

Degenerate Oligonucleotides

A library of homologs can also be generated from a set of degenerate oligonucleotide sequences. Chemical synthesis of a degenerate sequences can be carried out in an automatic DNA synthesizer, and the synthetic genes then ligated into an appropriate expression vector. The synthesis of degenerate oligonucleotides is known in the art (see for example, Narang, S A (1983) Tetrahedron 39:3; Itakura et al. (1981) Recombinant DNA, Proc 3rd Cleveland Sympos. Macromolecules, ed. A G Walton, Amsterdam: Elsevier pp 273-289; Itakura et al. (1984) Annu. Rev. Biochem. 53:323; Itakura et al. (1984) Science 198:1056; Ike et al. (1983) Nucleic Acid Res. 11:477. Such techniques have been employed in the directed evolution of other proteins (see, for example, Scott et al. (1990) Science 249:386-390; Roberts et al. (1992) PNAS 89:2429-2433; Devlin et al. (1990) Science 249: 404406; Cwirla et al. (1990) PNAS 87: 6378-6382; as well as U.S. Pat. Nos. 5,223,409, 5,198,346, and 5,096,815).

Generation of Analogs: Production of Altered DNA and Peptide Sequences by Directed Mutagenesis

Non-random or directed, mutagenesis techniques can be used to provide specific sequences or mutations in specific regions. These techniques can be used to create variants which include, e.g., deletions, insertions, or substitutions, of residues of the known amino acid sequence of a protein. The sites for mutation can be modified individually or in series, e.g., by (1) substituting first with conserved amino acids and then with more radical choices depending upon results achieved, (2) deleting the target residue, or (3) inserting residues of the same or a different class adjacent to the located site, or combinations of options 1-3.

Alanine Scanning Mutagenesis

Alanine scanning mutagenesis is a useful method for identification of certain residues or regions of the desired protein that are preferred locations or domains for mutagenesis, Cunningham and Wells (Science 244:1081-1085, 1989). In alanine scanning, a residue or group of target residues are identified (e.g., charged residues such as Arg, Asp, His, Lys, and Glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine). Replacement of an amino acid can affect the interaction of the amino acids with the surrounding aqueous environment in or outside the cell. Those domains demonstrating functional sensitivity to the substitutions are then refined by introducing further or other variants at or for the sites of substitution. Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined. For example, to optimize the performance of a mutation at a given site, alanine scanning or random mutagenesis may be conducted at the target codon or region and the expressed desired protein subunit variants are screened for the optimal combination of desired activity.

Oligonucleotide-Mediated Mutagenesis

Oligonucleotide-mediated mutagenesis is a useful method for preparing substitution, deletion, and insertion variants of DNA, see, e.g., Adelman et al., (DNA 2:183, 1983). Briefly, the desired DNA is altered by hybridizing an oligonucleotide encoding a mutation to a DNA template, where the template is the single-stranded form of a plasmid or bacteriophage containing the unaltered or wild type DNA sequence of the desired protein. After hybridization, a DNA polymerase is used to synthesize an entire second complementary strand of the template that will thus incorporate the oligonucleotide primer, and will code for the selected alteration in the desired protein DNA. Generally, oligonucleotides of at least 25 nucleotides in length are used. An optimal oligonucleotide will have 12 to 15 nucleotides that are completely complementary to the template on either side of the nucleotide(s) coding for the mutation. This ensures that the oligonucleotide will hybridize properly to the single-stranded DNA template molecule. The oligonucleotides are readily synthesized using techniques known in the art such as that described by Crea et al. (Proc. Natl. Acad. Sci. USA, 75: 5765, 1978).

Cassette Mutagenesis

Another method for preparing variants, cassette mutagenesis, is based on the technique described by Wells et al. (Gene, 34:315, 1985). The starting material is a plasmid (or other vector) which includes the protein subunit DNA to be mutated. The codon(s) in the protein subunit DNA to be mutated are identified. There must be a unique restriction endonuclease site on each side of the identified mutation site(s). If no such restriction sites exist, they may be generated using the above-described oligonucleotide-mediated mutagenesis method to introduce them at appropriate locations in the desired protein subunit DNA. After the restriction sites have been introduced into the plasmid, the plasmid is cut at these sites to linearize it. A double-stranded oligonucleotide encoding the sequence of the DNA between the restriction sites but containing the desired mutation(s) is synthesized using standard procedures. The two strands are synthesized separately and then hybridized together using standard techniques. This double-stranded oligonucleotide is referred to as the cassette. This cassette is designed to have 3' and 5' ends that are comparable with the ends of the linearized plasmid, such that it can be directly ligated to the plasmid. This plasmid now contains the mutated desired protein subunit DNA sequence.

Combinatorial Mutagenesis

Combinatorial mutagenesis can also be used to generate mutants. E.g., the amino acid sequences for a group of homologs or other related proteins are aligned, preferably to promote the highest homology possible. All of the amino acids which appear at a given position of the aligned sequences can be selected to create a degenerate set of combinatorial sequences. The variegated library of variants is generated by combinatorial mutagenesis at the nucleic acid level, and is encoded by a variegated gene library. For example, a mixture of synthetic oligonucleotides can be enzymatically ligated into gene sequences such that the degenerate set of potential sequences are expressible as individual peptides, or alternatively, as a set of larger fusion proteins containing the set of degenerate sequences.

Primary High-Throughput Methods for Screening Libraries of Peptide Fragments or Homologs

Various techniques are known in the art for screening generated gene products. Techniques for screening large libraries often include cloning the nucleic acids of interest into replicable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the genes under conditions in which detection of a desired activity, e.g., in this case, binding to a target organism or a surface component of a target organism, facilitates relatively easy isolation of the vector encoding the gene whose product was detected. Each of the techniques described below is amenable to high through-put analysis for screening large numbers of sequences created, e.g., by random mutagenesis techniques.

Display Libraries

In one approach to screening assays, the candidate peptides are displayed on the surface of a cell or viral particle, and the ability of particular cells or viral particles to bind an appropriate target organisms protein via the displayed product is detected in a "panning assay". For example, the gene library can be cloned into the gene for a surface membrane protein of a bacterial cell, and the resulting fusion protein detected by panning (Ladner et al., WO 88/06630; Fuchs et al. (1991) Bio/Technology 9:1370-1371; and Goward et al. (1992) TIBS 18:136-140). In a similar fashion, a detectably labeled ligand can be used to score for potentially functional peptide homologs. Fluorescently labeled ligands, e.g., target organisms, can be used to detect homologs which retain ligand-binding activity. The use of fluorescently labeled ligands, allows cells to be visually inspected and separated under a fluorescence microscope, or, where the morphology of the cell permits, to be separated by a fluorescence-activated cell sorter.

A gene library can be expressed as a fusion protein on the surface of a viral particle. For instance, in the filamentous phage system, foreign peptide sequences can be expressed on the surface of infectious phage, thereby conferring two significant benefits. First, since these phage can be applied to affinity matrices at concentrations well over 10.sup.13 phage per milliliter, a large number of phage can be screened at one time. Second, since each infectious phage displays a gene product on its surface, if a particular phage is recovered from an affinity matrix in low yield, the phage can be amplified by another round of infection. The group of almost identical E. coli filamentous phages M13, fd, and f1 are most often used in phage display libraries. Either of the phage gIII or gVIII coat proteins can be used to generate fusion proteins without disrupting the ultimate packaging of the viral particle. Foreign epitopes can be expressed at the NH.sub.2-terminal end of pIII and phage bearing such epitopes recovered from a large excess of phage lacking this epitope (Ladner et al. PCT publication WO 90/02909; Garrard et al., PCT publication WO 92/09690; Marks et al. (1992) J. Biol. Chem. 267:16007-16010; Griffiths et al. (1993) EMBO J 12:725-734; Clackson et al. (1991) Nature 352:624-628; and Barbas et al. (1992) PNAS 89:4457-4461).

A common approach uses the maltose receptor of E. coli (the outer membrane protein, LamB) as a peptide fusion partner (Charbit et al. (1986) EMBO 5, 3029-3037). Oligonucleotides have been inserted into plasmids encoding the LamB gene to produce peptides fused into one of the extracellular loophotosensitizer of the protein. These peptides are available for binding to ligands, e.g., to antibodies, and can elicit an immune response when the cells are administered to animals. Other cell surface proteins, e.g., OmpA (Schorr et al. (1991) Vaccines 91, pp. 387-392), PhoE (Agterberg, et al. (1990) Gene 88, 37-45), and PAL (Fuchs et al. (1991) Bio/Tech 9, 1369-1372), as well as large bacterial surface structures have served as vehicles for peptide display. Peptides can be fused to pilin, a protein which polymerizes to form the pilus-a conduit for interbacterial exchange of genetic information (Thiry et al. (1989) Appl. Environ. Microbiol. 55, 984-993). Because of its role in interacting with other cells, the pilus provides a useful support for the presentation of peptides to the extracellular environment. Another large surface structure used for peptide display is the bacterial motive organ, the flagellum. Fusion of peptides to the subunit protein flagellin offers a dense array of may peptides copies on the host cells (Kuwajima et al. (1988) Bio/Tech. 6, 1080-1083). Surface proteins of other bacterial species have also served as peptide fusion partners. Examples include the Staphylococcus protein A and the outer membrane IgA protease of Neisseria (Hansson et al. (1992) J. Bacteriol. 174, 4239-4245; Klauser et al. (1990) EMBO J. 9, 1991-1999).

In the filamentous phage systems and the LamB system described above, the physical link between the peptide and its encoding DNA occurs by the containment of the DNA within a particle (cell or phage) that carries the peptide on its surface. Capturing the peptide captures the particle and the DNA within. An alternative scheme uses the DNA-binding protein LacI to form a link between peptide and DNA (Cull et al., 1992, PNAS USA 89:1865-1869). This system uses a plasmid containing the LacI gene with an oligonucleotide cloning site at its 3'-end. Under the controlled induction by arabinose, a LacI-peptide fusion protein is produced. This fusion retains the natural ability of LacI to bind to a short DNA sequence known as LacO operator (LacO). By installing two copies of LacO on the expression plasmid, the LacI-peptide fusion binds tightly to the plasmid that encoded it. Because the plasmids in each cell contain only a single oligonucleotide sequence and each cell expresses only a single peptide sequence, the peptides become specifically and stably associated with the DNA sequence that directed its synthesis. The cells of the library are gently lysed and the peptide-DNA complexes are exposed to a matrix of immobilized receptor to recover the complexes containing active peptides. The associated plasmid DNA is then reintroduced into cells for amplification and DNA sequencing to determine the identity of the peptide ligands. As a demonstration of the practical utility of the method, a large random library of dodecapeptides was made and selected on a monoclonal antibody raised against the opioid peptide dynorphin B. A cohort of peptides was recovered, all related by a consensus sequence corresponding to a six-residue portion of dynorphin B (Cull et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89-1869).

This scheme, sometimes referred to as peptides-on-plasmids, differs in two important ways from the phage display methods. First, the peptides are attached to the C-terminus of the fusion protein, resulting in the display of the library members as peptides having free carboxy termini. Both of the filamentous phage coat proteins, pIII and pVIII, are anchored to the phage through their C-termini, and the guest peptides are placed into the outward-extending N-terminal domains. In some designs, the phage-displayed peptides are presented right at the amino terminus of the fusion protein. (Cwirla, et al. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 6378-6382). A second difference is the set of biological biases affecting the population of peptides actually present in the libraries. The LacI fusion molecules are confined to the cytoplasm of the host cells. The phage coat fusions are exposed briefly to the cytoplasm during translation but are rapidly secreted through the inner membrane into the periplasmic compartment, remaining anchored in the membrane by their C-terminal hydrophobic domains, with the N-termini, containing the peptides, protruding into the periplasm while awaiting assembly into phage particles. The peptides in the LacI and phage libraries may differ significantly as a result of their exposure to different proteolytic activities. The phage coat proteins require transport across the inner membrane and signal peptidase processing as a prelude to incorporation into phage. Certain peptides exert a deleterious effect on these processes and are underrepresented in the libraries (Gallop et al. (1994) J. Med. Chem. 37 (9): 1233-1251). These particular biases are not a factor in the LacI display system.

The number of small peptides available in recombinant random libraries is enormous. Libraries of 10.sup.7-10.sup.9 independent clones are routinely prepared. Libraries as large as 10.sup.11 recombinants have been created, but this size approaches the practical limit for clone libraries. This limitation in library size occurs at the step of transforming the DNA containing randomized segments into the host bacterial cells. To circumvent this limitation, an in vitro system based on the display of nascent peptides in polysome complexes has recently been developed. This display library method has the potential of producing libraries 3-6 orders of magnitude larger than the currently available phage/phagemid or plasmid libraries. Furthermore, the construction of the libraries, expression of the peptides, and screening, is done in an entirely cell-free format.

In one application of this method (Gallop et al. (1994) J. Med. Chem. 37 (9): 1233-1251), a molecular DNA library encoding 10.sup.12 decapeptides was constructed and the library expressed in an E. coli S30 in vitro coupled transcription/translation system. Conditions were chosen to stall the ribosomes on the mRNA, causing the accumulation of a substantial proportion of the RNA in polysomes and yielding complexes containing nascent peptides still linked to their encoding RNA. The polysomes are sufficiently robust to be affinity purified on immobilized receptors in much the same way as the more conventional recombinant peptide display libraries are screened. RNA from the bound complexes is recovered, converted to cDNA, and amplified by PCR to produce a template for the next round of synthesis and screening. The polysome display method can be coupled to the phage display system. Following several rounds of screening, cDNA from the enriched pool of polysomes was cloned into a phagemid vector. This vector serves as both a peptide expression vector, displaying peptides fused to the coat proteins, and as a DNA sequencing vector for peptide identification. By expressing the polysome-derived peptides on phage, one can either continue the affinity selection procedure in this format or assay the peptides on individual clones for binding activity in a phage ELISA, or for binding specificity in a completion phage ELISA (Barret, et al. (1992) Anal. Biochem 204,357-364). To identify the sequences of the active peptides one sequences the DNA produced by the phagemid host.

Secondary Screens

The high through-put assays described above can be followed by secondary screens in order to identify, enrich and select for molecules having appropriate affinity for a biological entity. Secondary screens depend on the ability of the targeting moiety to bind a polymer of interest. For example, a surface protein or carbohydrate of the target organism of interest can be used to identify ligands from a group of peptide fragments isolated though one of the primary screens described above. One may use highly pure materials, for example, purified protein from a viral pathogen, obtained from a recombinant organism specifically obtained for the purpose of production of this material, or one may use a crude preparation of the target organism, such as a cell-wall or pellicle preparation, even a heat-inactivated or formalin-treated preparation of the target organism.

The Examples below illustrate two examples of targeting materials, a polyamino acid of positive charge, polylysine, which has affinity for a broad range of bacterial species and can also serve as a backbone for coupling of additional targeting moieties; and the salivary protein histatin, which has affinity for several species of oral bacteria. Each of these materials can be used as a starting material in the procedures described for phage display library, described herein, for example by incorporation of the nucleic acid sequence into that of gene III of the M13 phage display vector (see, for example, Scott et al. (1990) Science 249:386-390; Roberts et al. (1992) PNAS 89:2429-2433; Devlin et al. (1990) Science 249: 404-406; Cwirla et al. (1990) PNAS 87: 6378-6382; as well as U.S. Pat. Nos. 5,223,409, 5,198,346, and 5,096,815). In this case, the target material for enrichment of the phage library may be bacterial cell wall fraction, isolated by sonication of the target organism in the cold in the presence of standard protease inhibitors, low speed centrifugation to separate cell walls from cytoplasm, and resuspension of wall material in buffer for use in several rounds of phage library binding selection. Procedures are described at length in U.S. Pat. No. 5,223,409. After two to three rounds of selection, phage bearing polyamino acid sequences or histatin variants of affinity to the target cell wall that is considerably enhanced over that of the starting material may be isolated. The sequence of the improved variants is readily determined by standard DNA sequence procedures, and the peptide can be produced in large quantity by standard peptide synthesis methods. Thus the procedures described here for generating fragments and analogs and testing them for enhanced affinity for the target organism are known in the art.

Target Organisms

Organisms to be targeted by the compositions and methods of the present invention are found on any light-accessible surfaces or in light-accessible areas, e.g., in human and animal subjects, on materials to be decontaminated, or on crop plants. In the cases of humans and animals, infections of the epidermis, oral cavity, nasal cavity, sinuses, ears, lungs, urogenital tract, and gastrointestinal tract are light accessible. Epidermal infections include those of unwanted organisms of bacterial, fungal, viral and animal origin, and include subcutaneous infections, especially localized lesions, for example caused by protozoans, parasites, or parasitic mites, which infections are light-accessible. Infections of the peritoneal cavity, such as those resulting from burst appendicitis, are light accessible via at least laparoscopic devices. A variety of skin infections which are refractory to antibiotics or long-term antifungal treatment, for example, dermatophycoses of the toenail, are suitable for PDT using the compositions of the invention.

A major area of application of compositions and methods of the invention are disorders and infections of the oral cavity, e.g., of the gums. Methods of the invention are particularly useful in treating oral infectious diseases, for example, periodontal diseases. Since pockets of periodontal disease infection occur within a few millimeters of the surface of the oral cavity, PDT offers significant advantages over the traditional physical methods of scaling and antibiotic therapy for this condition. Target oral unwanted organisms include a large number of bacterial and fungal species, e.g., Bacteroides species including B. gingivalis (now known as Porphyromonas gingivalis), Eikenella corrodens, Fusobacterium nucleatum, Wolinella recta, Eubacterium species, Prevotella (Bacteroides) intermedia, Bacteroides forsythus, Capnocytophaga species, Actinobacillus actinomycetamcomitans, and Streptococcus mutans.

Lung infection can occur with a variety of bacterial genera and species, which include the classical tuberculosis of Mycobacterium tuberculosis, the pseudomonads, which are the primary cause of death of cystic fibrosis patients, Klebsiella, and can also occur with a variety of virus strains. A variety of fungi and parasites are opportunistic pathogens of the lung, and Pneumocystis carinii infection is a common cause of death in immunocompromised AIDS patients. As pathogens of the lung are increasingly resistant to classical antibiotic therapies, PDT with the compositions of the instant invention offer an alternative method for eliminating these unwanted organisms that is independent of the microbial mechanisms of resistance. Additional epidermal infections and infections of deeper tissues arise from burns, scrapes, cuts, and puncture wounds. PDT with the compositions of the instant invention is useful for sterilization of such potential infectious sites, which can rapidly lead to toxic shock, a frequent concomitant of bullet wounds, and for treating the sites to eliminate or reduce unwanted infectious organisms. A major cause of infection in wounds, especially burns, is the Gram negative aerobic bacterium Pseudomonas. This organism produces an exotoxin which has been shown to retard wound healing. Multi-antibiotic resistant P. aeruginosa strains are becoming a significant problem, especially in burns units of large hospitals. Pseudomonads also produce fulminating infections of the cornea. Escherichia coli along with Staphylococcus aureus are the two most common bacteria in infected wounds.

Other sites of unwanted target organisms include the urogenital tract, the peritoneal cavity, the inner and outer ear, the nasal cavity and the gastrointestinal tract. Infectious sites of proliferation of unwanted target organisms in tissues of mesothelial and endothelial origin are also accessible to PDT by minimally invasive techniques.

Target organisms can be cellular or viral. Viruses which can be unwanted target organisms include any pathogenic life form comprising components of at least one nucleic acid molecule and one or more protein species, and may also include the enveloped viruses. Target organisms which are cells include at least a boundary cell membrane and are capable of energy production, nucleic acid synthesis, and contain ribosomes and are capable of ribosomal protein synthesis. Cells can be unicellular or multicellular, and said unicellular organisms can be prokaryotic or eukaryotic.

Prokaryotic target organisms can be bacteria, which bacteria can be Gram negative or Gram positive, or which are lacking cell walls. The Gram stain basis of distinguishing bacteria, based on whether or not cells of a specific strain or species of bacteria take up a stain, or are stained with the counterstain only, is known to those of skill in the art. Bacteria which are target organisms of the invention can be aerobic, anaerobic, facultatively anaerobic or microaerophilic. Spirochetes of the invention include but are not limited to the genera Borrelia and Treponema. This last genus contains species variously associated with the diseases of trenchmouth, pinta, and yaws, the latter two being tropical skin infections. Gram negative helical/vibroid motile bacterial genera suitable as target organisms include Campylobacter and Helicobacter. Gram negative aerobic and microaerophilic rods and cocci include the genera Bordetella, Neisseria, and Legionella. Facultatively anaerobic Gram negative rods include genera Pseudomonas, Salmonella, Shigella, Erwinia, Enterobacter, Erwinia, Escherichia, Vibrio, Haemophilus, Actinobacillus, Klebsiella and Salmonella. An important group of bacteria as target organisms for the present invention are the Gram positive cocci, including the genera Staphylococcus and Streptococcus, a strain of the latter known to cause a variety of infections including the childhood skin disease impetigo, and some strains of the former which are popularly designated, "flesh-eating bacteria." Gram positive rods include species of Listeria, suitable for treatment by the methods and compositions of the invention.

Bacteria suitable for photosensitizer composition treatment among those lacking rigid cell walls are the genus Mycoplasma. The actinomycete group includes several species of Mycobacterium that are suitable target organisms of the present invention. Additional bacterial genera which can be treated with the conjugate molecules of the invention include: Enterococcus, Leptospira, Serpulina, Mycoplasma, Bacteroides, Yersinia, Chlamydia, Vibrio, Actinobacillus, Porphyromonas, Hemophilus, Pasteurella, Peptostreptococcus, Propionibacterium, Corynebacterium and Dermatophilus. These and other bacterial groups and genera not listed here will be recognized by the skilled artisan as suitable target bacteria for the compositions of the invention.

Viruses that may be targeted by the compositions of the present invention include, but are not limited to, adenoviruses, herpesviruses, poxviruses, and retroviruses. Representative fungal target organism genera include but are not limited to, Cryptococcus, Blastomyces, Paracoccidioides, Candida, Aspergillus, Mycetoma, and include other genera causing various dermatomycoses.

Eukaryotic target organisms of the instant invention include unicellular protozoan and fungal pathogens and parasites, which can have a multicellular phase of the life cycle. Parasite infections of subjects are suitable for treatment by the compositions of the invention. Common parasites that infect or colonize the intestinal and urogenital tract include amoebae, flagellates, and nematodes. In addition, infection with trematodes, cestodes, ciliates, coccidian and microsporidian parasites may occur in these tracts. Members of the genera Leishmania and Onchocerca cause cutaneous ulcers, and of the genus Acanthamoeba can be found in corneal scrapings of the eye. Leishmania donovani causes the tropical ulcerating skin disease kala azar, which is suitable for treatment with the methods and compositions of the present invention. Intestinal tract genera that are suitable for targeting by compositions of the invention include Entamoeba, Giardia, Cryptosporidium, and microsporidia, pinworm, and helminth genera. Lung tissue can contain Pneumocystis carinii, and more rarely, amoebae such as Entamoeba, trematodes, or cestodes. The urogenital tract can be infected with Trichomonas, and with Schistosoma, which can be treated with compositions of the invention.

Viral, prokaryotic and eukaryotic target organisms are not limited to pathogens and parasites, and can include higher orders such as arthropods. Target organisms are not limited to pathogens and parasites of animal subjects, and can include plant pests.

These lists are used to illustrate applications of the present invention to major groups of suitable target organisms, but not to delimit the invention to the species, genera, families, orders or classes so listed.

Pharmaceutical Compositions

The compounds of the invention include conjugate molecules that have been formulated for topical administration, and also for administration to various external organs such as the outer ear, or organs accessible by external administration, such as by oral application or by lavage of the lung. The examples mentioned here are not intended as limiting with respect to the nature of the conjugate photosensitizer compositions of the invention, or to a particular route of the administration, and additional routes are listed herein. In another embodiment of the present invention, the photosensitizer compositions can be administered by combination therapy, i.e., combined with other agents. For example, the combination therapy can include a composition of the present invention with at least one other photosensitizer, at least one antibiotic, or other conventional therapy.

Photosensitizer conjugates that are somewhat insoluble in an aqueous solvent can be applied in a liposome, or a time release fashion, such that illumination can be applied intermittently using a regimen of periods of illumination alternating with periods of non-illumination. Other regimens contemplated are continuous periods of lower level illumination, for which a time-release formulation is suitable.

As used herein, the phrase "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. The use of such media and agents for pharmaceutically active substances is well known in the art. Preferably, the carrier is suitable for oral, intravenous, intramuscular, subcutaneous, parenteral, spinal or epidermal administration (e.g., by injection or infusion). Depending on the route of administration, the active compound may be coated in a material to protect the compound from the action of acids and other natural conditions that may inactivate the compound.

Conjugates of the invention can also be administered parenterally. The phrase "administered parenterally" as used herein means modes of administration other than oral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal, epidural and intrasternal injection and infusion.

A composition of the present invention can be administered by a variety of methods known in the art. As will be appreciated by the skilled artisan, the route and/or mode of administration will vary depending upon the desired results. The active compounds can be prepared with carriers that will protect the compound against rapid release, such as a controlled release formulation, including implants, transdermal patches, and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Many methods for the preparation of such formulations are patented or generally known to those skilled in the art. See, e.g., Sustained and Controlled Release Drug Delivery Systems, J. R. Robinson, ed., Marcel Dekker, Inc., New York, 1978.

Dosage regimens are adjusted to provide the optimum desired response (e.g., a therapeutic response). For example, a single bolus may be administered, several divided doses may be administered over time or the dose may be proportionally reduced or increased as indicated by the exigencies of the therapeutic situation.

One of ordinary skill in the art can determine and prescribe the effective amount of the pharmaceutical composition required. For example, one could start doses of the known or novel photosensitizer composition levels lower than that required in order to achieve the desired therapeutic effect and gradually increase the dosage until the desired effect is achieved.

OTHER EMBODIMENTS

The compositions of the invention can be used to decontaminate inanimate objects, such as medical and dental devices, heat-sensitive filters, surfaces of transilluminators, sonication probes, and any other surface that is light accessible and carries unwanted organisms. Many of these devices cannot be autoclaved, in which case the methods and compositions of the invention can be useful for decontamination.

The methods and compositions of the invention can be incorporated into a kit, which contain one or more of a photosensitizer which may or may not be coupled to a backbone, one or more target moieties, a coupling or cross-linking agent, buffers, and instructions for use. The user of the kit can select an appropriate target moiety to apply to the particular unwanted organism of choice. Two or more target moieties can be coupled to the photosensitizer-backbone, such that a broader range of unwanted organisms can be eliminated or substantially reduced by application of a single product.
 

Claim 1 of 26 Claims

1. A method of treating a subject, for a disorder characterized by the presence of an unwanted organism, comprising: administering to the subject a conjugate comprising a polylysine backbone to which is coupled a targeting moiety and a porphyrin photosensitizer, wherein the targeting moiety is a cationic antimicrobial peptide; irradiating the subject with energy of wavelength appropriated to produce a cytotoxic effect by the photosensitizer; thereby treating the subject, for the disorder characterized by the presence of an unwanted organism, wherein the unwanted organism is a bacterium and is located in the oral cavity including throat and tonsil, in the sinus, in the ear, in the nose, in the peritoneal cavity, or on the epidermis.
 

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