Viremia and antibody responses of chipmunks and squirrels inoculated with La Crosse (LAC) and Trivittatus (TVT) viruses were determined and compared. High level viremias were detected in 5 of 6 chipmunks (Tamias striatus griseus), and 4 of 5 gray squirrels (Sciurus carolinensis) infected with LAC virus. Only 2 of 6 chipmunks infected with TVT virus developed detectable viremias. No associated clinical disease was noted. Neutralizing antibody persisted for at least 200 days in all chipmunks with LAC virus while in two of those inoculated with TVT virus it was detectable for only 140 days. Squirrels inoculated with LAC virus produced an antibody pattern similar to that in chipmunks but the titers were lower. None of the 4 gray squirrels inoculated with TVT virus had a detectable serologic response. Antibody appearing after a single inoculation of either LAC or TVT virus showed partial heterologous neutralizations of LAC, TVT, snowshoe hare (SSH), and Jamestown Canyon (JC) viruses. Transmission of LAC virus from infected chipmunks and squirrels to suckling mice was accomplished with Aedes triseriatus mosquitoes.
Department of Preventive Medicine, University of Wisconsin.
On leave of absence from the Faculty of Graduate Studies, Mahidol University, Bangkok, Thailand.
Department of Veterinary Science, University of Wisconsin.