Rabies Vaccines for Wildlife
Since the first proof of principle experimental study in the 1970s, oral rabies vaccines have gained a great reputation in controlling and eliminating rabies in wildlife. Starting with classically attenuated virus vaccines derived from only a few virulent rabies virus field isolates, oral rabies vaccination (ORV) for the first time has offered new opportunities and opened new avenues worldwide in fighting this fatal zoonosis in particular in its canine wildlife reservoir hosts. Beyond classical approaches, biotechnological tools have been increasingly used to generate new oral rabies vaccines with the aim to improve safety, immunogenicity, and efficacy in the various canine wildlife reservoir species. While heterologous vector systems have been developed for expression of the immune-dominant glycoprotein (G) of rabies virus (RABV), recent advancements in recombinant DNA technology and virus reverse genetics helped facilitating vaccine development through targeted modifications and directed attenuation of rabies virus constructs. Unlike in humans, pets, and livestock, there is no alternative way yet to efficiently vaccinate canine wildlife reservoir hosts at a population level other than using modified live virus vaccines. In contrast to any other vaccines for veterinary use, next to safe and efficacious vaccine constructs, attractive species-specific baits, as well as a well-defined distribution system/strategy, are indispensable components of any oral rabies vaccine for wildlife. As baits play a decisive role for successful application in the field they are an integral part of the licensing procedure. This chapter summarizes the state-of-the-art information on oral rabies virus vaccines for wildlife and provides an outlook on the challenges of vaccine development for wildlife for the future.