Comparative analyses of members of the Venezuelan equine encephalomyelitis virus complex.

Polyacrylamide gel electrophoretic examination of viruses selected from the Venezuelan equine encephalomyelitis (VEE) complex revealed distinct strain to strain differences in profiles of the two virion envelope proteins. The core protein was identical in all viruses tested. We detected five electrophoretic patterns into which the virus strains could be classified and these were designated alpha (alpha), beta (beta), gamma (gamma), delta (delta), and episolon (episolon). Isolates representing variant E of subtype I exhibited a profile characterized by only one apparent envelope band. The epizootic subtypes I-A, I-B, I-C and the sylvatic subtype II viruses contained at least two envelope proteins which differed in molecular weight according to virus strain but which were not necessarily specific for antigenic variety. These results generally, though not uniformly, support the serologic classification of the VEE virus complex and suggested that the usefulness of the classification scheme could be complemented by the inclusion of biochemical criteria.