There is provided vaccine compositions for intranasal administration, which compositions comprise one or more antigens and an effective adjuvant amount of a chitosan.

Description of the Invention

BACKGROUND OF THE INVENTION

Vaccines are preparations of antigenic materials, administered to recipients with a view to enhancing resistance to infection by inducing active immunity to specific microorganisms, for example bacteria or viruses.

Vaccines, which may be as single or mixed component vaccines, are presented in a variety of forms. For example, current influenza vaccines consist of either inactivated whole virus, disrupted virus (split vaccines) or purified preparations of antigenic proteins.

Vaccines are typically administered parenterally via injections. Traditional parenteral immunization regimes are known to have a number of drawbacks. For example, many individuals possess a natural fear of injections and may experience psychological discomfort as a result. Furthermore, many individuals find injections physically uncomfortable. Moreover, parenteral vaccination (e.g. intramuscular, sub-cutaneous etc.) is not an effective means of eliciting local antibody production if there has been no previous local exposure (e.g. by way of infection).

An effective local and/or topical administration regime is therefore desirable.

In the case of some diseases, it would be advantageous to stimulate the mucosal immune system. In order to do this, the vaccine must be applied topically to a mucosal surface. Thus, in certain cases (e.g. in the case of infections of the upper respiratory tract), it would be beneficial to obtain more effective stimulation of the local mucosal immune system of the respiratory tract.

Accordingly, a number of attempts have been made to develop mucosal vaccines. One drawback, however, is that inactivated vaccines are often poorly immunogenic when given mucosally. In order to overcome this problem, different approaches to improving the immunogenicity of vaccines given orally or intranasally have included the use of adjuvants (see below), encapsulation of the vaccine in a variety of microspheres, and the use of live attenuated strains.

Certain adjuvants have been shown, when co-administered with vaccine antigens, to further boost the effectiveness of vaccine compositions by stimulating the immune response (see e.g. Hibberd et al., Ann. Intern. Med., 110, 955 (1989)). Examples of adjuvants that have been shown to be effective include interferon alpha, Klebsiella pneumoniae, glycoprotein, and interleukin-2.

Chitosans are derivatives of chitin or poly-N-acetyl-D-glucosamine in which the greater proportion of the N-acetyl groups have been removed through hydrolysis.

European Patent Application 460 020 discloses pharmaceutical formulations, including chitosans, as mucosal absorption enhancers. That the chitosan could provide an adjuvant effect when administered in a vaccine composition is neither disclosed nor suggested.

BRIEF SUMMARY OF THE INVENTION

Provided are vaccine compositions for intranasal administration. The compositions include one or more antigen and an effective adjuvant. Also provided are methods if immunizing a mammal against diseases by administering the compositions to the mammal, methods of enhancing the immunogenicity of intranasally administered antigens, and use of antigens in combination with an adjuvant for the manufacture of a vaccine composition for intranasal administration to immunize a mammal against specific diseases.

It has been found that, upon intranasal co-administration, chitosan enhances the immune response of antigens and thus provides an adjuvant effect.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly, in a first aspect of the invention, there is provided a vaccine composition adapted for intranasal administration, which composition comprises antigen and an effective adjuvant amount of a chitosan (hereinafter referred to as "the compositions according to the invention").

The term "effective adjuvant amount" will be well understood by those skilled in the art, and includes an amount of a chitosan which is capable of stimulating the immune response to nasally administered antigens, i.e., an amount that increases the immune response of a nasally administered antigen composition, as measured in terms of the IgA levels in the nasal washings. Suitably effective increases in IgA levels include by more than 5%, preferably by more than 25%, and in particular by more than 50%, as compared to the same antigen composition without any adjuvant.

Preferred concentrations of the chitosan in the compositions according to the invention are in the range 0.02 to 10%, more preferably 0.1 to 5%, and particularly 0.25 to 2%.

It has been found that, by administration of an antigen together with a particular chitosan derivative in an intranasal composition, it is possible to achieve an immune (e.g., IgG and IgA) response. It has also been found that, if a chitosan is incorporated into intranasal vaccine compositions containing an antigen, good systemic and local immune responses are produced. In particular, we have found that the intranasal administration of the compositions according to the invention enhances both a protective IgA mucosal immune response and an IgG systemic immune response.

Thus, the invention further provides a method of enhancing a protective IgA mucosal immune response and an IgG systemic immune response by administering intranasally to a mammal a vaccine composition comprising an antigen and an effective adjuvant amount of a chitosan.

The antigen may be provided as a sub-unit of a cell wall protein or polysaccharide, or as a deoxyribonucleic acid molecule (DNA molecule) which produces the antigen in the cells after introduction of the DNA molecule to the cell (e.g., by transfection). Strictly speaking, the DNA is not itself an "antigen" but it encodes the antigen and is termed antigen herein.

The antigen may further be provided in a purified or an unpurified form. However, it is preferred that the antigen to be provided in a purified form.

The invention may be applied to antigens including proteins from pathogens, recombinant proteins, peptides, polysaccharides, glycoproteins, lipopolysaccharides, and DNA molecules (polynucleotides).

The following list of antigens is provided by means of illustration and is not meant to be exclusive: influenza virus antigens (such as haemagglutinin and neuraminidase antigens), Bordetella pertussis antigens (such as pertussis toxin, filamentous haemagglutinin, pertactin), human papilloma virus (HPV) antigens, Helicobacterpylori antigens, rabies antigens, tick-borne encephalitis (TBE) antigens, meningococcal antigens (such as capsular polysaccharides of serogroup A, B, C, Y and W-135), tetanus antigens (such as tetanus toxoid), diphtheria antigens (such as diphtheria toxoid), pneumococcal antigens (such as Streptococcus pneumoniae type 3 capsular polysaccharide), tuberculosis antigens, human immunodeficiency virus (HIV) antigens (such as GP-120, GP-160), cholera antigens (such as cholera toxin B subunit), staphylococcal antigens (such as staphylococcal enterotoxin B), shigella antigens (such as shigella polysaccharides), vesicular stomatitis virus antigen (such as vesicular stomatitis virus glycoprotein), cytomegalovirus (CMV) antigens, hepatitis antigens (such as hepatitis A (HAV), B (HBV), C (HCV), D (HDV) and G (HGV) virus antigens), respiratory syncytial virus (RSV) antigens, herpes simplex antigens, or combinations thereof (e.g. combinations of diphtheria, pertussis and tetanus (DPT)). Suitable antigens also include those delivered for induction of tolerance, such as retinal antigens.

Preferred antigens include Bordetella pertussis antigens, meningococcal antigens, tetanus antigens, diphtheria antigens, pneumococcal antigens, tuberculosis antigens, and RSV antigens.

According to a further aspect of the invention, preferably the antigen is not an influenza virus antigen.

Preferably, the chitosan is water-soluble, and may advantageously be produced from chitin by deacetylation to a degree of greater than 40%, preferably between 50% and 90%, and more preferably between 70% and 95%, deacetylation.

Particular deacetylated chitosans that may be mentioned include the "SEA CURE.sup.+.TM." chitosan glutamate available from Protan Biopolymer A/S. Drammen, Norway.

The molecular weight of the chitosan may be between 10 kD and 500 kD, preferably between 50 kD and 300 kD and more preferably between 100 kD and 300 kD.

The compositions according to the invention may be used in the immunization of a host against diseases, for example as described in the tests below.

According to a further aspect of the invention, there is provided a method of immunizing a host against infection by disease, which method comprises administering intranasally to the host a vaccine composition comprising antigen together with an effective adjuvant amount of a chitosan as hereinbefore defined.

Moreover, according to a further aspect of the invention, there is provided a method of enhancing the immune response of an intranasally administered antigen, which method comprises co-administration of said antigen and a chitosan as hereinbefore defined.

The intranasal compositions according to the invention can be formulated as liquids or dry powders, for administration as aerosols, drops, or insufflations.

It is preferred that the compositions according to the invention are formulated as dry powders or in the form of microspheres.

Compositions for administration as nasal drops may contain one or more excipients of the type usually included in such compositions, for example preservatives, viscosity adjusting agents, tonicity adjusting agents, buffering agents and the like.

In order to ensure that the chitosan remains soluble in an aqueous medium, and to ensure also that the antigen is not adversely affected by too acidic a pH, a solution for intranasal administration preferably has a pH in the range 5.5 to 6.5, most preferably approximately pH 6.

Also provided is a means for dispensing the intranasal compositions of purified surface antigen and chitosan. A dispensing device may, for example, take the form of an aerosol delivery system, and may be arranged to dispense only a single dose, or a multiplicity of doses.

The vaccine will be administered to the patient in an amount effective to stimulate a protective immune response in the patient. For example, the vaccine may be administered to humans in one or more doses, each dose containing 1-250 micrograms and more preferably 2-50 micrograms of protein or polysaccharide antigen prepared from each viral or bacterial strain. For example, where haemagglutinin and neuraminidase preparations are prepared from three virus strains, e.g. 2 x Influenza A and I x Influenza B, a total dose of viral protein administered may be in the range 15-150 micrograms. Where Bordetella persussis antigens are employed, a total dose of bacterial protein administered as FHA, pertussis toxin (toxoid) or pertactin, either individually or in combination may be in the range 5-150 micrograms.

Claim 1 of 21 Claims

1. A vaccine composition for intranasal administration comprising an antigen selected from the group consisting of a polysaccharide, a lipopolysaccharide, a polynucleotide, a whole cell, and a virus selected from the group consisting of inactivated whole viruses, disrupted viruses and live attenuated viruses, admixed with an effective adjuvant amount of a chitosan, wherein the chitosan has a molecular weight in a range of 10 kD to 500 kD, and the chitosan is a chitin that is more than 40% deacetylated.

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