Prevenção e controle do Vaccinia virus no Brasil: padronização de um sistema prime-boost para imunização e determinação de seus hospedeiros naturais

Abstract

The Poxviridae family comprises large and complex viruses that infect vertebrates and invertebrates. Orthopoxvirus (OPXV) is a Poxviridae familys genus, and comprises species with clinical and veterinary relevance, like Variola virus, Cowpox virus, 5 Monkeypox Virus and Vaccinia virus (VACV). VACV has been associated with bovine vaccine outbreaks in Brazil, causing ulcerative lesions in cattle and humans, causing economical losses and social impact. Since 1999, several bovine vaccine outbreaks were notified in Brazil, and many strains of VACV were isolated during such outbreaks. There are few available data about VACV hosts and reservoirs in Brazil. In addition, little is known about how these viruses are maintained in nature and the role of wild life in the emergence of those outbreaks. Despite the impacts associated to VACV outbreaks, there are no available safe vaccines against such zoonosis. Thus, the present work aimed the search of VACV natural hosts and reservoirs, and the study of safe vaccines against bovine vaccinia. Studies for discovery VACV hosts were performed using wild animals sera collections from Brazilian forests and to capturing rodents in properties affected by bovine vaccinia outbreaks. In parallel, three vaccines against VACV were tested: an inactive Brazilian VACV strain,named BAV; and two DNA vaccines, codifying B5R and H3L viral glycoproteins. Serological and molecular evidences indicated VACV infection in peridomestic rodents, captured in Minas Gerais State rural areas, as such as in two Amazon monkey species. The vaccine studies showed that BAV in association with B5R-DNA vaccine, using rime-boostimmunization, presented the best results. Therefore, the results here obtained suggest the existence of a feral VACV cycle of life, and that peridomestic rodents could carrier VACV between forests and rural areas. Our results also showed that safe vaccines against VACVcould be good alternatives to prevent bovine vaccinia outbreaks. The results of the present study could be used for prevention and control programs against VACV in the future