Recombinant veterinary vaccines against rabies : state of art and perspectives

Abstract

The “One Health” concept summarized the idea that the health both of human and animal is interdependent and is bound to the health of the ecosystems in which they exist. This notion is supported and implemented by the World Organization for Animal Health to understand risks for human and animal health (including companion animals, livestock and wildlife) and ecosystem health as a whole. In this context, the best strategy to control zoonotic pathogens (transmitted by domestic or wild animals to humans and vice versa) is vaccination of the animal source, together with an adequate epidemiological surveillance program. Rabies is a zoonotic disease that affects humans, wildlife, companion animals, and livestock. Even though there are pre- and postrabies exposure treatments available for humans, it is more cost-effective over the long term to eliminate rabies in its natural terrestrial reservoirs. Currently, dogs are vaccinated with conventional inactivated vaccines while a viral vector–based vaccine (canarypox virus) is being used for cats. Several countries from the northern hemisphere control the sylvatic rabies reservoirs (coyotes, red foxes, raccoon dogs, and raccoons) using attenuated rabies vaccines or recombinant viral-vectored vaccines (based on vaccinia virus or human adenovirus). Lastly, vaccination of calves, horses, and other domestic livestock species (African and South American camels, goats, and pigs) is performed with inactivated conventional vaccines. Inactivated vaccines against rabies are effective but present several disadvantages such as uncertain antigen composition, manipulation of the pathogen during the vaccine manufacturing, need of cold chain during storage, and transportation and inability to differentiate vaccinated from infected animals. To overcome these inconveniences, the actual tendency is the rational design of recombinant immunogens (viral-vectored or subunit vaccines) that are safe and efficacious against pathogens. This chapter presents a revision of viral-vectored vaccines against rabies currently used in the veterinary field and the perspectives of new recombinant immunogens.