EFFECT OF VESICULAR STOMATITIS-VIRUS MATRIX PROTEIN ON HOST-DIRECTED TRANSLATION IN-VIVO

Vesicular stomatitis virus infection causes a rapid and potent inhibit ion of both host transcription and translation. Recently, the viral ma trix (M) protein was shown to inhibit host-directed transcription in v ivo in the absence of any other viral component (B. L. Black and D. S. Lyles, J. Virol. 66:4058-4064, 1992). The goal of this study was to d etermine the effect of M protein on host-directed translation. In vitr o-transcribed mRNAs encoding M protein and chloramphenicol acetyltrans ferase (CAT) were cotransfected into BHK cells to determine the effect of M protein expression on translation of CAT mRNA. The results prese nted here show that M protein did not inhibit host-directed translatio n of CAT mRNA. On the contrary, this study gave the unexpected result that M protein actually stimulated host-directed translation under the same conditions in which it potently inhibited host-directed transcri ption. Under these conditions, the combined effect on host gene expres sion was a greater-than-20-fold inhibition. Furthermore, the enhanceme nt of host translation mediated by M protein was genetically correlate d with M protein's ability to inhibit host transcription. Thus, the re sults of this study establish that M protein does not inhibit host pro tein synthesis under the same conditions in which it potently inhibits host transcription and suggest that the inhibition of transcription a nd that of translation by vesicular stomatitis virus require separate viral gene products.