Rabies is an acute and deadly disease caused by a viral infection of the central nervous system, most often spread by a bite and saliva from an infected (rabid) animal (e.g., bats, raccoons, skunks, foxes, ferrets, cats, or dogs). The number of deaths due to rabies each year is estimated to be between 40,000-70,000. As it is for many zoonotic diseases, the only way to protect humans is to eliminate the disease in the animal reservoir. Parenteral rabies vaccination is feasible for owned dogs and other pets, whereas oral vaccination is required for wild and stray animals, with the delivery of rabies vaccine within a food or bait. Currently, about 15 states distribute edible rabies vaccines for wild animals in an attempt to eradicate the disease. The problem with these vaccines is that they are not stable in environmental conditions and are easily destroyed in the animal's gastrointestinal (GI) system. There is great need for a new oral rabies vaccine delivery system for animals. The vaccine must be protected from sunlight, high ambient temperatures and humidity. In addition, it must be protected from the damaging effect of gastric juice and bile in the duodenum. The product should readily and instantly dissolve in the animal's mouth, not be destroyed by manual and/or aerial bait distribution. We propose to combine two technologies to prepare a novel form of rabies vaccine that should have good yield, will be cost effective and should be stable at ambient temperatures and more stable traversing the stomach and duodenum. Preservation by Vaporization (PBV) was invented by the PI, has a pending patent and immobilizes sensitive biologicals in the """"""""glass state"""""""" so they are stable at ambient temperatures. Alginate gel encapsulation has been used for several years in the industry to protect vaccines from damage in the GI system. We propose to use PBV to dry fresh rabies vaccine encapsulated in alginate gel microspheres.
The specific aims are: 1.) Formulate a protocol for drying of rabies vaccines for animals using PBV technology. Demonstrate stability of the dry preserved vaccines at 37oC and 60oC 2.) Develop alginate gel micro spheres (with an average diameter of about 100 ?) comprised of the viral particles and the preservation solution with minimum (less than 10%) loss of the virus by leaching or leaking from the particles. 3.) Formulate a protocol for drying of rabies vaccines encapsulated in the alginate microspheres using PBV technology. Demonstrate stability of the dry preserved vaccines at 37oC and 60oC. The short term stability at 60oC is needed to entrap the vaccines in eatable hydrogenated oils or fats to ensure protection from ambient humidity. The long-range goal of this project is to produce bait that is stable in the wild, would be eaten by wild animals and will not be destroyed in the GI tract, so it will produce a strong immune response in the intestine. UST will partner with CDC and Merial Inc. who will provide vaccine and perform viability assays.
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 |
