Epidemiologic implications of the genetic variations of bluetongue virus.

The segmented RNA genome of bluetongue (BT) virus (BTV) provides for considerable diversity. This diversity has been seen in biochemical and biophysical analyses of the numerous strains of BTV as well as in clinical and immunologic responses of ruminant animals to BTV infection. This report describes the preliminary characterization of a unique BTV serotype 11 population recovered during 4 months in 1982 from 40 naturally infected animals including cattle, sheep and a goat. The strains of BTV serotype 11 were mild in their pathogenicity for the ruminants as no clinical signs of disease were seen. Infected cattle did not always develop detectable precipitating (P) or neutralizing (N) antibody during or after the infection. A better understanding of the epidemiology of BT may result from studies that include host and vector studies along with biochemical and biophysical characterization of the infecting BTV population.