Rabies is a deadly disease, estimated to cause 40-70 thousand deaths per year. It is most often spread by a bite and saliva from an infected wild or feral animal (e.g., bats, raccoons, skunks, foxes, ferrets, cats, or dogs). Oral vaccines in bait have been successful with animals that chew their food, thus allowing the vaccine bait to come into contact with the mouth and throat mucosa to elicit the immune response. However, canid species (dogs, foxes, coyotes) ,the primary vectors of the disease to humans, do not chew their food or the bait; rather it gulped down causing the vaccine to be destroyed in the stomach acid. For our Phase 1 project, we combined two technologies to prepare a novel form of rabies vaccine, designed to be stable at ambient temperatures and in harsh environments, such as during the journey through stomach acid and bile secretion on its way to the small intestine where we propose it can immunize the animal through the intestinal mucosa. The PI's patent pending """"""""Preservation by Vaporization"""""""" (PBV) technology which immobilizes sensitive biologicals in the """"""""glass state"""""""" so they are stable at ambient temperatures has been utilized with alginate gel encapsulation to protect vaccines from heat and chemical damage. UST utilized PBV to dry-preserve two alginate-encapsulated vaccines VRG (vaccinia-based) and ERA (Rabies based). We exceeded our original target specifications for vaccine stability during 1 hour equilibration at 60?C, and after 2 weeks at 37?C.
The specific aims of the Phase II project are to: 1) Optimize formulation of dry preserved rabies vaccines encapsulated in alginate gel microspheres. 2) Formulate Rabies Vaccine Animal Bait Nucleus (RVABN) filled with VRG and with ERA vaccines. 3) Evaluate efficacy of the vaccine products in animal studies - specifically foxes and dogs - against a rabies challenge. The long-range goal of this project is to produce an oral vaccine for rabies secreted in bait that is stable in the wild. This vaccine, once eaten by wild animals will not be destroyed in the GI tract and will produce a strong immune response in the intestine. UST will partner with CDC and Merial Ltd. who will provide the vaccine and help to perform animal studies.
The number of deaths that rabies causes each year is estimated to be between 40,000- 70,000. The cost of living with rabies in America is high and growing, exceeding $300 million per year. Although rabies vaccinations have been available for domestic animals for many years, only recently have such preventive measures been developed to control rabies in wildlife. Development of baits that would have stable rabies vaccines embedded in edible hydrogenated oils such that the vaccines are protected from the elements, including sunlight, temperature, humidity and gastric juices, could allow vaccination of wild animals so they do not get rabies, and thus could help eradicate the disease.
| Smith, Todd G; Wu, Xianfu; Ellison, James A et al. (2017) Assessment of the immunogenicity of rabies vaccine preserved by vaporization and delivered to the duodenal mucosa of gray foxes (Urocyon cinereoargenteus). Am J Vet Res 78:752-756 |
| Smith, Todd G; Siirin, Marina; Wu, Xianfu et al. (2015) Rabies vaccine preserved by vaporization is thermostable and immunogenic. Vaccine 33:2203-2206 |
