Title:  Process for the preparation of immunogens or diagnostic reagents, and immunogens or diagnostic reagents thereby obtainable

United States Patent:  6,541,210

Issued:  April 1, 2003

Inventors:  Felici; Franco (Rome, IT); Luzzago; Alessandra (Rome, IT); Monaci; Paolo (Rome, IT); Nicosia; Alfredo (Rome, IT); Cortese; Riccardo (Rome, IT)

Assignee:  Istituto di Recerche di Biologia Moleculare P. Angeletti S.p.A. (Pomezia RM, IT)

Appl. No.:  441992

Filed:  November 18, 1999

A process for the preparation of immunogens or diagnostic reagents that mimic an antigen or a pathogenic organism specific to a disease, essentially characterized by the following operations: identification of at least one antibody that reacts with the antigen or pathogenic organism specific to the disease; construction of phage libraries which display on the surface of the capsid oligopeptides, expressed from random sequence oligonucleotidic inserts introduced into a gene coding for a phage capsid protein using genetic manipulation techniques (for example, using a plasmid engineered for the purposes of the invention, the genetic map of which is shown in the figure); selection of the phages that display on the surfaces of the capsid antigenic oligopeptides recognized by said antibody; optional use of the selected phages and/or fragments thereof and/or their derivatives for the formulation of diagnostic kits for the specific pathogenic agent, or in general for the disease, including immunological disorders typical of so-called autoimmune diseases, with known or unknown etiology and/or pathogenesis; optional use of the selected phages and/or fragments thereof and/or their derivatives to induce a tolerance of the phenomena of hypersensitivity and/or allergy to compounds and/or natural or synthetic preparations; optional immunization of an organism by means of the selected phages and/or fragments thereof and/or their derivatives; and optional verification of the presence, in the serum of the immunized organism, of antibodies that recognize the above antigen or organism specific to the disease.

DESCRIPTION OF THE INVENTION

The subject of the present invention is a process for the preparation of immunogens or diagnostic reagents that mimic an antigen or a pathogenic organism specific to a disease, even if this is uncharacterized or even unknown (thereby including auto-immune diseases whose etiology and/or pathogenesis is known or unknown). This process is based on the existence and availability of antibodies, both monoclonal or polyclonal, or of serum containing antibodies, which react specifically with the organism causing the infection.

Antibodies suitable for use in this process can be specific for any antigen of interest for which an immunogen or diagnostic reagent that mimes the antigen is sought. The antigen can be a protein or peptide whether synthetic, derived from a natural source, or produced recombinantly; carbohydrate; polysaccharide; glycoprotein; hormone; receptor; antibody; virus; substrate; metabolite; transition state analog; cofactor; drug; dye; nutrient; growth factor; cellular component; oncogene product; bacteria and their extracellular products; mammalian cells and extracts therefrom including tumor cells, virus infected cells and normal cells; parasites; protozoa; malarial antigens; helminths; fungi; rickettsia; or an allergen including but not limited to pollens, dusts, danders or extracts of the same; or a venom, poison, toxin, or toxoid; nucleic acids including DNA; or any other antigen without limitation. Antigens of viruses which are suitable for use in the present invention include antigens from the viruses including but not limited to polio virus, influenza virus, HIV, HTLV, papilloma virus, adeno virus, parainfluenza virus, measles virus, mumps virus, respiratory syncytial virus, shipping fever virus, Western and Eastern encephalomyelitis virus, Japanese B encephalomyelitis virus, Russian spring-summer encephalomyelitis virus, hog cholera virus, hepatitis virus, pox virus, rabies, virus, distemper virus, herpes virus, cytomegalo virus, foot and mouth disease virus, rhinovirus, Newcastle disease virus, vaccinia virus; and pseudorabies virus. The mime can be an immunogen, a vaccine, an inhibitor or activator, etc. without limitation.

As is known, all vaccines and diagnostic reagents currently on sale or undergoing clinical tests are conventionally obtained by means of processes based on the manipulation, modification and/or adaptation of pathogenic organisms or components thereof. These methods have given good results, but are not without problems. The greatest limitation associated with these methods is connected with the fact that they depend upon the availability of information and/or material directly deriving from pathogenic organisms or components thereof.

Previous attempts to overcome the above described limitation have so far failed for a lack of an efficient and reproducible experimental protocol; in particular, these attempts did not provide sufficient information in order to identify and characterize immunogenic mimics to be used for diagnosis and vaccine therapy. It must be emphasized that the present invention is focused on the development of a new technology aimed at overcoming conceptual and technical inadequacies of previously proposed protocols.

A key feature of the present invention is a novel strategy for the selection of antigenic and immunogenic mimics, based on the use, as reagents, of serum samples from patients and a counter-selection step utilizing serum samples from healthy individuals.

Use of the process for preparation according to the present invention allows this limitation to be overcome, furthermore offering additional advantages which will be clear from the following description.

The process for the preparation of immunogens or diagnostic reagents that mimic an antigen or a pathogenic organism specific to a disease--according to the present invention--is essentially characterized by the following operations:

identification of at least one antibody that reacts with the antigen or pathogenic organism specific to the disease;

construction of phage libraries which display on the surface of the capsid oligopeptides, expressed from random sequence oligonucleotidic inserts introduced into a gene coding for the phage capsid using genetic manipulation techniques;

selection of the phages that display on the surfaces of the capsid antigenic oligopeptides with a first pathologic serum in order to identify phage that display oligopeptides that react with all or most of the sera tested, and counter-screening with a panel of sera from another set of individuals taken as control in order to identify oligopeptides that do not react with all or most sera from controlled individuals;

optional use of the selected phages and/or fragments thereof and/or their derivatives for the formulation of diagnostic kits for the specific pathogenic agent, or in general for the diseases, including immunological disorders typical of so-called autoimmune diseases, with known or unknown etiology and/or pathogenesis;

optional use of the selected phages and/or fragments thereof and/or their derivatives for the formulation of an antagonist of the antigen-antibody reactions for treatment of the disease induced by said antigen;

optional use of the selected phages and/or fragments thereof and/or their derivatives to induce a tolerance of the phenomena of hypersensitivity and/or allergy to compounds and/or natural or synthetic preparations;

optional immunization of an organism by means of the selected phages and/or fragments thereof and/or their derivatives; and

optional verification of the presence, in the serum of the immunized organism, of antibodies that recognize the above antigen or organism specific to the disease.

The construction of phage libraries, according to the present invention, can be advantageously performed using the filamentous phages M13, F1 and Fd, or derivatives thereof. The reasons for this are the following:

filamentous phages are commonly used as molecular vectors in the field of molecular biology and genetic engineering. For example, by taking advantage of their feature to contain a genome with a single DNA helix, they have been particularly used in DNA sequencing experiments, in direct site mutagenesis experiments and for the expression of proteins and peptides;

the information required and sufficient for encapsidation of a single chain DNA genome has been well characterized and can be transferred to other molecular vectors;

it has likewise been demonstrated that at least two proteins of the capsid of filamentous phages can be modified by means of the addition or insertion of additional amino acid sequences. The resulting phages are encapsidated, maintain their ability to replicate and, in most cases, to infect bacterial cells. The foreign amino acid sequences are displayed on the surface of the phage, and can be recognized by interaction with antibodies or with other specific molecules according to the case.

The antibodies that can be used in the process for the preparation of immunogens and diagnostic reagents according to the present invention can be monoclonal antibodies, polyclonal antibodies, or antibodies contained in sera. The latter form of embodiment is of particular interest, because it provides for the first time a reproducible experimental strategy to identify novel antigenic and immunogenic mimics in absence of any information on the structure and properties of the natural and pathological antigen.

The gene coding for the phage capsid, with random sequence oligonucleotidic inserts, can be the gene coding for the protein VIII of the phage capsid or the gene coding for the protein III of said capsid.

The process according to the invention can be applied without restriction to any antibody or organism responsible for illness. Good results have been obtained using monoclonal antibodies, or sera specific for the surface antigen of the human hepatitis B virus (HBsAg).

The antigenic oligopeptides recognized by the antibodies used can be obtained by expression from random sequence oligonucleotidic inserts, using as a vector, for example, the plasmid pC89.

In the process for the preparation of immunogens and diagnostic reagents according to the present invention, it is possible to select phages containing in their capsid form the site identifying the restriction enzyme EcoRI (GAATTC) to that identifying the restriction enzyme BamHI (GGATCC), one of the aminoacidic sequences SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:7 and SEQ ID NOS:9 to 47.

The present invention is not limited to the process for the preparation of immunogens or diagnostic reagents against a specific pathogenic agent, but also extends to the immunogens and diagnostic reagents obtainable using the process illustrated above, and to the phages usable in the process mentioned above.

Furthermore, the invention also extends to the plasmids pC89 containing, wholly or in part, a nucleotidic sequence chosen from the group comprising the sequences SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6 and SEQ ID NO:8.

The present invention refers also to oligopeptides obtainable by the above process which react with pathological sera from individuals affected by the same disease affecting the patients whose sera have been used for the selection and screening of phage displaying said oligopeptides and which do not react with sera from individuals not affected by the same disease. The above oligopeptides are capable of eliciting in a living organism an immune response against the natural antigens or antibodies against HCV or antibodies against HBV.

Subject matter of the present invention is also the use of the above oligopeptides as immunogens to elicit an antibody response against specific pathological antigens, such as for instance infectious pathogens, in the case said elicited antibodies also being protective or neutralizing, to formulate a vaccine against said pathogenic agents.

The immunogens obtained from the process of the present invention are useful as vaccines or immunizing agents as well as being useful as diagnostic reagents. The vaccines or immunizing agents are administered to a patient in need of such treatment according to standard methods known in the art. The vaccine or immunizing agents can be administered and used either singly or in combination. The vaccines and immunogens of the present invention can comprise the phage or protein and peptides isolated therefrom.

Kits containing the immunogens obtained from the process of the present invention may be prepared. Such kits are used to detect the presence of the antigen in a sample. Such characterization is useful for a variety of purposes including but not limited to forensic analyses and epidemiological studies. Such a kit would comprise a compartmentalized carrier suitable to hold in close confinement at least one container. The carrier would further comprise reagents such as the immunogens, and antibodies suitable for detecting the antigens. The carrier may also contain a means for detection such as labeled antigen or enzyme substrates or the like.

Pharmaceutically useful compositions comprising the immunogens and vaccines of the present invention, may be formulated according to known methods sun as by the admixture of a pharmaceutically acceptable carrier. Examples of such carriers and methods of formulation may be found in Remington's Pharmaceutical Sciences. To form a pharmaceutically acceptable composition suitable for effective administration, such compositions will contain an effective amount of the vaccine or immunogen of the present invention.

Therapeutic or diagnostic compositions of the invention are administered to an individual in amounts sufficient to treat or diagnose the relevant disorders. The effective amount may vary according to a variety of factors such as the individual's condition, weight, sex and age. Other factors include the mode of administration The pharmaceutical compositions may be provided to the individual by a variety of routes such as subcutaneous, topical, oral and intramuscular.

The present invention also has the objective of providing suitable topical, oral systemic and parenteral pharmaceutical formulations for use in the novel methods of treatment of the present invention. The compositions containing vaccine or immunogens identified according to this invention as the active ingredient can be administered in a wide variety of therapeutic dosage forms in conventional vehicles for administration. For example, the vaccines and immunogens can be administered in such oral dosage forms as tablets, capsules (each including timed release and sustained release formulations), pills, powders, granules, elixirs, tinctures, solutions, suspensions, syrups and emulsions, or by injection. Likewise, they may also be administered in intravenous (both bolus and infusion), intraperitoneal, subcutaneous, topical with or without occlusion, or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. An effective but non-toxic amount of the vaccines and immunogens can be employed.

The daily dosage of the vaccines and immunogens may be varied over a wide range from 0.01 to 1000 mg per adult human/per day. For oral administration, the vaccines and immunogens are preferably provided in the form of scored or unscored tablets containing 0.01, 0.05, 0.1, 0.5, 1.0, 2.5, 5.0, 10.0, 15.0, 25.0, and 50.0 milligrams of the active ingredient for the symptomatic adjustment of the dosage to the patient to be treated. An effective amount of the vaccines and immunogens is ordinarily supplied at a dosage level of from about 0.0001 mg/kg to about 100 mg/kg of body weight per day. The range is more particularly from about 0.001 mg/kg to 10 mg/kg of body weight per day. The dosages of the vaccines and immunogens are adjusted when combined to achieve desired effects. On the other hand, dosages of these various agents may be independently optimized and combined to achieve a synergistic result wherein the pathology is reduced more than it would be if either agent were used alone.

Advantageously, vaccine or immunogens of the present invention may be administered in a single dose, or a single daily dose, or the total daily dosage may be administered in divided doses of two, three or four times daily. Furthermore, vaccine or immunogens for the present invention can be administered in intranasal form via topical use of suitable intranasal vehicles, or via transdermal routes, using those forms of transdermal skin patches well known to those of ordinary skill in that art. To be administered in the form of a transdermal delivery system, the dosage administration will, of course, be continuous rather than intermittent throughout the dosage regimen.

For combination treatment with more than one active agent, where the active agents are in separate dosage formulations, the active agents can be administered concurrently, or they each can be administered at separately staggered times.

The dosage regimen utilizing the vaccine or immunogens of the present invention is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient; and the particular vaccine or immunogen thereof employed. A physician or veterinarian of ordinary skill can readily determine and prescribe the effective amount of the vaccine or immunogens of the present invention required to prevent, counter or arrest the progress of the condition. Optimal precision in achieving concentrations of the vaccine or immunogens of the present invention within the range that yields efficacy without toxicity requires a regimen based on the kinetics of the vaccine or immunogens of the present invention availability to target sites. This involves a consideration of the distribution, equilibrium, and elimination of the vaccine or immunogens of the present invention.

In the methods of the present invention, the vaccine or immunogens herein described in detail can form the active ingredient, and are typically administered in admixture with suitable pharmaceutical diluents, excipients or carriers (collectively referred to herein as "carrier" materials) suitably selected with respect to the intended form of administration, that is, oral tablets, capsules, elixirs, syrups and the like, and consistent with conventional pharmaceutical practices.

For instance, for oral administration in the form of a tablet or capsule, the active vaccine or immunogen component can be combined with an oral, non-toxic pharmaceutically acceptable inert carrier such as ethanol, glycerol, water and the like. Moreover, when desired or necessary, suitable binders, lubricants, disintegrating agents and coloring agents can also be incorporated into the mixture. Suitable binders include, without limitation, starch, gelatin, natural sugars such as glucose or beta-lactose, corn sweeteners, natural and synthetic gums such as acacia, tragacanth or sodium alginate, carboxymethylcellulose, polyethylene glycol, waxes and the like. Lubricants used in these dosage forms include, without limitation, sodium oleate, sodium stearate, magnesium stearate, sodium benzoate, sodium acetate, sodium chloride and the like. Disintegrators include, without limitation, starch, methylcellulose, agar bentonite, xanthan gum and the like.

For liquid forms the active vaccine or immunogen component can be combined in suitably flavored suspending or dispersing agents such as the synthetic and natural gums, for example, tragacanth, acacia, methylcellulose and the like. Other dispersing agents which may be employed include glycerin and the like. For parenteral administration, sterile suspensions and solutions are desired. Isotonic preparations which generally contain suitable preservatives are employed when intravenous administration is desired.

Topical preparations containing the active vaccine or immunogen component can be admixed with a variety of carrier materials well known in the art, such as, e.g. alcohols, aloe vera gel, allantoin, glycerine, vitamin A and E oils, mineral oil, PPG2 myristyl propionate, and the like to form, e.g. alcoholic solutions, topical cleansers, cleansing creams, skin gels, skin lotions, and shampoos in cream or gel formulations.

The vaccine or immunogens of the present invention can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine or phosphatidylcholines.

Vaccine or immunogens of the present invention may also be delivered by the use of monoclonal antibodies as individual carriers to which the vaccine or immunogen molecules are coupled. The vaccine or immunogens of the present invention may also be coupled with soluble polymers as targetable vaccine or immunogen carriers. Such polymers can include polyvinyl-pyrrolidone, pyran copolymer, polyhydroxypropylmethacryl-amidephenol, polyhydroxy-ethylaspartamidephenol, or polyethyl-eneoxidepolylysine substituted with palmitoyl residues. Furthermore, the vaccine or immunogens of the present invention may be coupled to a class of biodegradable polymers useful in achieving controlled release of a vaccine or immunogen, for example, polyactic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydro-pyrans, polycyanoacrylates and cross-linked or amphipathic block copolymers of hydrogels.

Up to this point a general description has been given of the subjects of the present invention. With the assistance of the following examples, a more detailed description will now be given of specific embodiments of the invention, aimed at giving a better understanding of the objects, characteristics, advantages and methods of application thereof. The following examples refer, respectively, to embodiments of the process for the preparation of immunogens and diagnostic reagents against a specific pathogenic agent, according to the present invention; to a demonstration of the effectiveness of the clones selected for preparation of immunogens based on the effects produced by samples of serum from test animals immunized using the single clones; and to a demonstration of the effectiveness of the clones selected for preparation of diagnostic reagents, based on their specific reaction with the serum of individuals immunized with HBsAg.

The single figure enclosed shows a portion of the genetic map of the plasmid pC89 engineered for the purposes of the invention. The nucleotidic sequence for the restriction sites and the corresponding aminoacidic sequence are illustrated below the portion of the above mentioned genetic map. The wild-type aminoacidic sequence of the amino-terminal end of mature pVIII has been modified in order to introduce single EcoRI and BamHI sites.

Claim 1 of 8 Claims

What is claimed is:

1. A method for immunizing an organism comprising

a) producing a peptide that mimics an antigen or a pathogenic organism specific to a disease, comprising the steps of:

(i) collecting serum samples from at least two patients whose sera contain antibodies to the antigen or pathogenic organism and from at least one control individual whose serum would not be expected to contain antibodies to the antigen or pathogenic organism;

(ii) contacting the antibodies from the serum sample from said first patient with a phage-displayed random peptide library and selecting a first pool of phages which are bound by antibodies present in the serum sample from said first patient;

(iii) contacting the phages in said first pool of phages with the antibodies from a serum sample from said second patient and selecting a second group of phages that are bound by antibodies present in samples from both said first patient and from said second patient;

(iv) contacting phages from the second group with serum from said control individual to identify phages that are not bound by antibodies contained in the sera from said control individual; and

(v) if a phage is bound by antibodies in the sera from at least both said first and second patients but is not bound by antibodies confined in the serum from said control individual, identifying a peptide displayed by said phage and producing said peptide that mimics said antigen or said pathogenic organism to contain the amino acid sequence of said peptide displayed by said phage; and

b) administering an effective amount of said peptide to said organism to induce an immune response.
 

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