A Survey of Electropherotype Relationships of Bluetongue Virus Isolates from the Western United States

The genome profiles of 200 field isolates of bluetongue virus were obtained by extracting the double-stranded RNA genome from each isolate and separating the ten genome segments by polyacrylamide gel electrophoresis. These virus isolates, consisting of representatives of the four bluetongue virus serotypes existing in the U.S.A., were obtained during an epidemiological study commencing in 1979 in four western states of the United States. Analysis of the migration patterns of the ten double-stranded RNA genome segments revealed distinct variations of electrophoretic profiles of many isolates. These variations are discussed in relation to the year and geographical region in which the isolate was made, the species of animal from which the virus was obtained and the electropherotype relationships of the four bluetongue virus serotypes existing in the U.S.A.