Vaccine compositions comprising a water-in-oil emulsion, immunogen-loaded hydrogel particles, and cationic polymer

1. A vaccine composition comprising:

a water-in-oil emulsion;

a plurality of hydrogel particles loaded with an immunogen dispersed in the aqueous phase of the water-in-oil emulsion, and

a biocompatible cationic polymer attached to the hydrogel particles;

wherein a portion of the immunogen is partitioned within the hydrogel particles to provide for a persistent dose and a portion of the immunogen is partitioned within the biocompatible cationic polymer attached to the hydrogel particles to provide for an initial priming dose.

2. A vaccine composition according to claim 1 , wherein that substantially all of the immunogen is sequestered in the hydrogel particles and/or in the biocompatible cationic polymer.

3. A vaccine composition according to claim 1 , wherein the cationic polymer is attached as a continuous shell surrounding the hydrogel particles.

4. A vaccine composition according to claim 1 , wherein the cationic polymer is attached as a non-continuous shell surrounding the hydrogel particles.

5. A vaccine composition according to claim 3 , such that control is achieved over the ratio of primary dose and the sustained release dose by control of the weight ratio of the hydrogel particle core to the surrounding shell.

6. A vaccine composition according to claim 1 , wherein the portion of the immunogen partitioned within the biocompatible cationic polymer is characterised to be about 5% to 70% of the total immunogen dose within the composition.

7. A vaccine composition according to claim 1 , wherein the hydrogel particles comprise a biocompatible anionic polymer and the cationic polymer is electrostatically complexed with the anionic polymer.

8. A vaccine composition according to claim 7 , wherein the % wt/wt ratio of the anionic polymer and cationic polymer is about 1:10 to about 10:1, preferably about 1:4 to about 4:1.

9. A vaccine composition according to claim 7 , wherein the hydrogel particles comprise a crosslinked anionic polysaccharide.

10. A vaccine composition according to claim 9 , wherein the hydrogel particles comprise crosslinked alginate.

11. A vaccine composition according to claim 1 , wherein the cationic polymer is a cationic polysaccharide.

12. A vaccine composition according to claim 11 , wherein the cationic polysaccharide is chitosan.

13. A vaccine composition according claim 1 , wherein the immunogen is a particulate immunogen.

14. A vaccine composition according to claim 13 , wherein the particulate immunogen is a virus-like particle, pathogen mimicking particle, or bacterial vaccine.

15. A vaccine composition according to claim 14 , wherein the immunogen is a virus-like particle selected from the group consisting of Hepatitis B, Hepatitis E, human papilloma virus, chikungunya virus, influenza, foot and mouth disease (FMD), human immunodeficiency virus (HIV), Zika virus, Actinobacillus pleuropneumoniae (previously Haemophilus pleuropneumoniae ), Haemophilus parasuis ( H. parasuis ), Streptococcus suis , Foot and Mouth Disease (FMD), Cattle Viral Diarrhea (Pestivirus) (BVDV), Bovine herpesvirus (BHV-1) causing Infectious bovine rhinotracheitis (IPV) and/or Infectious pustular vulvovaginitis (IPV), and Rabies.

16. A vaccine composition according to claim 1 , wherein the water-in-oil emulsion comprises an adjuvanting oil.

17. A vaccine composition according to claim 16 , wherein the water-in-oil emulsion comprises a surfactant with the adjuvanting oil.

18. A vaccine composition according to claim 1 , comprising:

a water-in-oil emulsion;

a plurality of alginate particles loaded with particulate immunogens dispersed in the aqueous phase of the water-in-oil emulsion, and

chitosan surrounding and complexed with the alginate particles.

19. A vaccine composition according to claim 18 , wherein a portion of the immunogen is partitioned within the alginate particles to provide for a persistent dose and a portion of the immunogen is partitioned within the chitosan surrounding with said alginate particles in the form of a continuous shell to provide for an initial priming dose, and wherein the weight ratio of the hydrogel core to the surrounding shell is preferably 1:4 to 4:1 to achieve control of the immunogen release profile across a primary dose and sustain release.

20. A vaccine composition according to claim 18 , wherein the water-in-oil emulsion comprises an adjuvant that produces a water-in-oil emulsion or water-in-oil-in-water emulsion.

21. A method of delivering an immunogen to a subject for the treatment or prevention of a disease or disorder in the subject, the method comprising the step of administering the vaccine composition of claim 1 to the subject by injection.