Nucleotide sequences of the 26S mRNAs of the viruses defining the Venezuelan equine encephalitis antigenic complex.

Genetic relationships among viruses defining the Venezuelan equine encephalitis (VEE) virus antigenic complex were determined by analyzing the 3'-terminal 561 nucleotides of the nonstructural protein 4 gene and the entire 26S RNA region of the genome. New sequence information is reported for VEE 78V-3531 (VEE subtype-variety IF), Mucambo (IIIA), Tonate (IIIB), 71D-1252 (IIIC), Pixuna (IV), Cabassou (V), and AG80-663 (VI) viruses. The results reported here and by previous investigators largely support the current classification scheme of these viruses, while clearly identifying Everglades (II) as a subtype I virus. A genetic relationship between 78V-3531 (IF) and AG80-663 (VI) viruses contradicted previous serologic results. Mutations near the amino terminus of the E2 envelope proteins of Pixuna and AG80-663 viruses probably account for the previously reported low reactivity of the protective monoclonal antibody 1A2B-10 with these two viruses. Variations in the distribution of potential glycosylation sites in the E2 glycoprotein are discussed.