The interaction of antibody with the major surface glycoprotein of vesicular stornatitis virus II. Monoclonal antibodies to nonneutralizing and cross-reactive epitopes of Indiana and New Jersey serotypes

Eleven monoclonal antibodies reactive with the major surface glycoprotein (G-protein) of vesicular stomatitis virus serotypes Indiana and New Jersey (VSV-Ind, VSV-NJ) were used to map antigenic sites found on one or both serotypes. The antibodies used were unable to neutralize infectivity of the virus in vitro although they were able to bind to the G-protein. Six of the antibodies bound to the G-proteins of both serotypes and delineated three nonoverlapping epitopes as determined by a competitive binding assay. In addition, one monoclonal antibody bound to both serotypes and could neutralize infectivity in vitro of only VSV-Ind. This antibody could compete with several cross-reactive nonneutralizing antibodies which could not neutralize either VSV-Ind or VSV-NJ. Three monoclonal antibodies were serotype specific for VSV-NJ and exhibited no overlap among themselves or with the cross-reactive antibodies. One VSV-Ind serotype-specific antibody was isolated which could compete with a cross-reactive antibody. Enhancement of antibody binding by the binding of a second antibody was observed in some cases. This phenomenon appeared to be due to an increase in availability of antigenic sites caused by allosteric modifications.