Monoclonal antibodies to the matrix protein of vesicular stomatitis virus (New Jersey serotype) and their effects on viral transcription.

Of 33 hybridomas raised by immunization of BALB/c mice with the matrix (M) protein of the New Jersey serotype of vesicular stomatitis virus (VSV), 17 secreted monoclonal antibodies (mAb) of the IgG isotype and, unexpectedly, 16 of the IgM isotype. All these monoclonal antibodies bound strongly to VSV-New Jersey M protein by ELISA, immunoprecipitation, and immunoblotting assays, but exhibited only slight or no cross-reactivity with the M protein of VSV-Indiana. Four antigenic determinants of VSV-New Jersey M protein could be identified by competitive binding of 125I-labeled monoclonal antibodies but three of these epitopes exhibited partial overlap. Monoclonal antibodies to two epitopes reversed the inhibitory effect of M protein on in vitro transcription of VSV-New Jersey ribonucleoprotein. However, monoclonal antibodies to the other two epitopes had little effect on M-protein transcription inhibition but actually increased significantly the transcriptional inhibitory effect of M protein under certain experimental conditions. Monoclonal antibodies to all four epitopes reacted strongly with the M protein of the tsC1 mutant of VSV-New Jersey which is restricted in transcription inhibition.