A serological survey was conducted in Iowa to determine the prevalence rate of California group virus antibodies in sera of several vertebrate species. Serum specimens were assayed for infectivity-neutralizing antibody in a microneutralization system with baby hamster kidney cell culture. Of 77 sera assayed, 21 (27%) neutralized trivittatus (TVT) virus infectivity. The antibody prevalence rate was highest for eastern cottontail rabbits inasmuch as 46% (10/22) of the serum specimens from this species possessed neutralizing activity. Other vertebrate species having TVT virus antibody included the fox squirrel, 29% (7/24), opossum, 12% (3/25), and raccoon, 17% (1/6). One cottontail rabbit serum neutralized both TVT virus and Jamestown Canyon (JC) virus infectivity, and one opossum serum specimen neutralized JC virus. None of the vertebrate sera neutralized La Crosse, St. Louis encephalitis, or western equine encephalomyelitis virus infectivity. Trivittatus virus neutralizing antibody was detected in the sera of sentinel rabbits, and TVT virus was isolated from the blood collected from one of these sentinels shortly after the first population peak of adult Aedes trivittatus mosquitoes in 1973. The implications of these data and the possibility of transovarial transmission of TVT virus in A. trivittatus are discussed.
Present address: Department of Entomology, Walter Reed Army Institute of Research, Washington, D. C. 20012.
Present address: State Hygienic Laboratory of Iowa, University of Iowa, Iowa City, Iowa 52242.