Strain-dependent Virulence Characteristics of Bluetongue Virus Serotype 11

Department of Pathology, School of Veterinary Medicine, University of California, Davis, California 95616, U.S.A. Two strains of bluetongue virus (BTV) serotype 11, UC-2 and UC-8, were identified by the electrophoretic migration pattern of their genomic RNA segments on polyacrylamide gel electrophoresis. Significant differences in virulence of these two viruses could be demonstrated by subcutaneous inoculation of newborn mice. No signs of disease were observed in mice infected with UC-2. Mice infected with UC-8 died of a severe necrotizing encephalitis, which resembled lesions in bovine and ovine foetuses infected with BTV. Keywords: orbivirus, BTV, virulence, murine Received 12 November 1985; accepted 9 January 1986.