Development of a Nanoparticle Vaccine Delivery System with Polymeric Oral Adjuvants for Poultry

Development of new vaccination technology has been hindered by a lack of new adjuvants to enable development of protective immunity using different vaccine delivery methods. A vaccine delivery system using oral adjuvants would be applicable across species for both individual and mass vaccination in both the medical and veterinary fields. We sought to create an oral nanoparticle (NP) vaccine delivery system that is easy to produce and uses polymers as oral adjuvants with killed virus. Our hypothesis was gelatin and chitosan would enhance viral uptake and stimulate immune cells to produce protective immunity. This would allow the safer killed form of each virus to be used in place of modified live (MLV) viruses and avoid undesirable side effects like immunosuppression. The research objectives were to

1. Fabricate and characterize gelatin NPs encapsulating inert materials of similar size and shape to the viruses of interest for fabrication proof-of-concept

2. Modify the NP delivery system to minimize immune cell cytoxicity for the vaccine delivery application

3. Fabricate and characterize FPV and HEV viral nanoparticles' stability, cellular uptake/infectivity, and released viruses' ability to replicate

4. Compare the abilities of the killed HEV nanovaccine, killed HEV with loose gelatin and chitosan polymers (no nanoparticle), and a live HEV commercial vaccine to induce textit{in vivo} seroconversion, protective immunity, and side effects during clinical and challenge studies in turkeys

We proved our hypothesis to be correct in addition to demonstrating matching the encapsulation material size to empty NP size leads to preferred encapsulated NP formulation parameters, chitosan stabilizes the NP formulation bypassing the need for cytotoxic crosslinkers, and paraformaldehyde is able to kill virus prior to vaccine formulation while still preserving virus morphology sufficiently for immune cell recognition. This development constitutes one of the first novel adjuvants discoveries in 70 years and opens the door for conversion of injectable vaccines to oral delivery across species.