Synthetic peptides of Venezuelan equine encephalomyelitis virus E2 glycoprotein. III. Identification of a protective peptide derived from the carboxy-terminal extramembranal one-third of the protein.

To complete our analysis of the E2 glycoprotein of Venezuelan equine encephalomyelitis (VEE) virus, we prepared six synthetic peptides corresponding to the extramembranal carboxy-terminal one-third of the protein. NIH-Swiss mice were immunized with the peptides, and antipeptide and antiviral titers were determined by enzyme-linked immunosorbent assay (ELISA). Challenge studies revealed that peptide 13 (amino acids 241-265) protected 60-70% of virus-challenged mice. Although the other peptides generally elicited antipeptide ELISA titers but no or low antiviral titers and did not protect mice, significant E2 reactivity was found in immunoblots. These results provide the first direct evidence that much of the E2 carboxy-terminal domain is cryptic in the VEE virion, even when virus was bound to polystyrene ELISA plates.