In an arbovirus surveillance program in Wisconsin, 11 Bunyamwera-group virus agents, among others, were isolated and identified during the years 1964–1967. Each isolation was from Aedes mosquitoes except one from Mansonia perturbans. Each isolation was made in suckling mice, and identifications were made by complement fixation, hemagglutination inhibition, agar-gel-diffusion, and virus neutralization in mice. Each agent was ethersensitive and produced sickness and death in weanling as well as in suckling mice. Four of the 11 isolates produced usable hemagglutinating antigen; the others have so far failed. Evidence of a relation of certain of the Wisconsin Bunyamwera-group isolates to recognized members of the California encephalitis group of viruses was seen in each of the four serologic procedures employed. Apparent annual fluctuation was noted in amount of Bunyamwera-group virus present in mosquitoes in the same study areas during the period of this observation, as indicated by successful isolations.
Present address: Man and Animals Branch, ERD, ARS. USDA, Betsville, Maryland 20705.
Present address: Department of Bacteriology and Parasitology, Faculty of Veterinary Medicine, Aristotelian University, Thessaloniki, Greece.