PREVALENCE OF BLUETONGUE VIRUS EXPRESSION IN LEUKOCYTES FROM EXPERIMENTALLY INFECTED RUMINANTS

Replication of bluetongue virus (BTV) in leukocytes from the blood of sheep, cattle, elk, and mule deer inoculated with BTV serotype 10 or 1 7 was assessed by immunocytochemical staining and dot blot northern hy bridization to determine if differences in the prevalence of infection in this blood fraction might account for the differences in clinical disease among these species. Viremia was confirmed by virus isolation in all inoculated animals. Analysis of leukocytes with monoclonal anti bodies specific for BTV proteins revealed low numbers of infected leuk ocytes in only 2 sheep 8 days after inoculation with BTV serotype 10. Most of the cells expressing BTV were identified morphologically as mo nocytes; approximately 10% of infected cells were lymphocytes. Blueton gue virus was not detected by use of dot-blot hybridization on samples of blood. Our results suggest that differential infection of leukocyt es does not account for the pronounced differences in clinical signs a nd pathologic changes among ruminants.