Biochemical and antigenic comparisons of the envelope glycoproteins of Venezuelan equine encephalomyelitis virus strains

Pulse-chase experiments after synchronous initiation of translation indicate that the Venezuelan equine encephalomyelitis (VEE) virus membrane glycoprotein, E₂, is derived by proteolytic cleavage of the precursor, PE₂. The structural proteins of VEE virus strains representing each of the antigenic subtypes and varieties have been compared by discontinuous SDS-polyacrylamide gel electrophoresis. Nucleocapsid proteins of all isolates were similar in size (mol. wt. 35 to 36x10³). The mol. wt. of E₁ varied from 48 to 51x10³ and the mol. wt. of E₂ glycoproteins ranged from 53 to 59x10³. Pixuna virus contained a third envelope glycoprotein of 59x10³ mol. wt.in addition to the two major glycoproteins of mol. wt. 53x10³ and 48x10³ respectively. The isoeletric points (pI) of E₁ and E₂ for all VEE stains studied were approx. 7 and 9 respectively. Both glycoproteins of TC-83 virus induced precipitating antibodies which reacted only with the homologous purified E₁ and E₂ glycoproteins. Antibodies to E₂ protein of each virus neutralized virus infectivity and inhibited the agglutination of goose erythrocytes by virions. Haemagglutination-inhibition tests using antisera to E₂ glycoproteins of prototype viruses, representing each of the antigenic subtypes and varieties, differentiated the viruses into subtypes I, II, III and IV with subtype I divided into variants 1AB, 1C, 1D and 1E.