Compositions and methods for encapsulating vaccines for the oral vaccination and boostering of fish and other animals

1. A composition for oral delivery, comprising one or more pharmaceutically active agents constituting in total from about 0.05% to about 10% w/w of the composition, one or more bio-adhesive polymers selected from the group consisting of chitosan, dimethyl chitosan, trimethyl chitosan, carboxymethyl chitosan and mixtures thereof and constituting in total from about 0.05% to about 10% w/w of the composition, and one or more short chain polysaccharides or oligosaccharides constituting in total from about 0.05% to about 30% w/w of the composition, wherein the composition is a crosslinked solid;

wherein said one or more pharmaceutically active agents are selected from the group consisting of immunogenic peptides, immunogenic proteins, intact inactive viral particles, attenuated viral particles, infectious viral particles, intact killed prokaryotes, attenuated prokaryotes, infectious prokaryotes, intact killed protozoans, attenuated protozoans, infectious protozoans, intact killed multicellular pathogens, attenuated multicellular pathogens, infectious multicellular pathogens, recombinant subunit vaccines, recombinant vectors encoding immunogenic proteins, recombinant vectors for delivering and expressing genes encoding immunogenic proteins, and mixtures of any of these, and wherein the composition further comprises one or more adjuvant compounds.

2. The composition of claim 1 , wherein the one or more adjuvant compounds are selected from the group consisting of beta-glucans, squalene, and squalane, and are present in total in an amount from about 0.1% to about 20% w/w based on the weight of the composition.

3. The composition of claim 1 , wherein said one or more short chain polysaccharides or oligosaccharides are selected from the group consisting of inulins, maltodextrins, cyclodextrins and mixtures thereof.

4. A method of preparing the composition according to claim 1 , comprising:

(i) preparing an acidic aqueous solution comprising at least one bioadhesive polymer, wherein the bioadhesive polymer is chitosan and the acidic aqueous solution has a pH low enough to gelatinize the chitosan;

(ii) combining a short chain polysaccharide or oligosaccharide into the acidic aqueous solution;

(iii) combining the pharmaceutically active agent with an adjuvant selected from the group consisting of beta-glucan, squalene and squalane oil in a solution or a water in oil emulsion;

(iv) adding the solution or emulsion of step (iii) into the product of step (ii); and

(v) precipitating or extruding the product of step (iv) into a cross-linking solution comprising a crosslinking agent to form a solid product.

5. The method of claim 4 , wherein the short chain polysaccharide or oligosaccharide is selected from inulin, maltodextrins and cyclodextrins.

6. The method of claim 4 , wherein the composition comprises from about 0.1% to about 10% of the adjuvant compound.

7. The method of claim 4 , wherein the adjuvant compound is selected from beta-glucans.

8. The method of claim 4 , wherein in step (iii) the pharmaceutical agent is in said water in oil emulsion.

9. The method of claim 4 , wherein the crosslinking agent comprises from about 1% to about 20% of phosphate or carbonate anions.

10. The method of claim 4 , wherein the crosslinking solution further comprises about 1% to 30% of a sugar.

11. The method of claim 4 , wherein the crosslinking solution further comprises about 1% to 30% of an alcohol.

12. The composition according to claim 1 , wherein the crosslinked solid is combined with a thickening agent selected from the group consisting of methylcellulose, pectin, alginate, xanthan gum, carboxymethyl cellulose and hydroxypropyl cellulose.

13. The composition according to claim 12 , further comprising feed pellets upon which the composition is top-coated.

14. The composition according to claim 1 , produced by a method comprising

(i) preparing an acidic aqueous solution comprising at least one bioadhesive polymer, wherein the bioadhesive polymer is chitosan and the acidic aqueous solution has a pH low enough to gelatinize the chitosan;

(ii) combining a short chain polysaccharide or oligosaccharide into the acidic aqueous solution;

(iii) combining the pharmaceutically active agent with an adjuvant selected from the group consisting of beta-glucan, squalene and squalane oil in a solution or a water in oil emulsion;

(iv) adding the solution or emulsion of step (iii) into the product of step (ii); and

(v) precipitating or extruding the product of step (iv) into a cross-linking solution comprising a crosslinking agent to form a solid product;

wherein in step (iii) the pharmaceutically active agent is in said water in oil emulsion.

15. A method of orally vaccinating or boostering an animal against a pathogen, comprising the steps of:

dispersing or spraying a liquid mixture comprising the composition of claim 14 and a liquid carrier onto an animal feed; and

delivering the resulting animal feed to the animal at a similar or greater dose of immunogenic agent than is usually provided by injection or immersion.

16. The method of claim 15 , wherein the delivery is repeated every three days for up to ten feeding events to maximize immunogenicity.