The effect of poliovirus infection on the translation In Vitro of VSV messenger ribonucleoprotein particles

Abstract

Messenger ribonucleoprotein (mRNP) particles were isolated and examined for the presence of factors involved in the inhibition of protein synthesis induced by poliovirus infection. Vesicular stomatitis virus (VSV) mRNNs were used as a model for cellular mRNNs. These mRNNs were translated in HeLa cell extracts with a similar efficiency and optimal conditions to that of purified mRNA, but they were not translated in extracts prepared from poliovirus-infected HeLa cells, which have been shown to be defective in cap-binding protein activity. We conclude that mRNP proteins do not include cap-binding protein activity, since the mRNNs were not able to bypass the restriction on translation of capped mRNAs in polio-infected cell extracts. In addition, VSV mRNNs were isolated from polio-superinfected cells, in which their translation was inhibited. These mRNNs were translated in vitro as well as normal VSV mRNNs. No evidence of a modification or a blocking factor on the mRNNs which prevented their translation following polio infection was observed. Thus, within the limits of the in vitro translation assays used, no factors involved in the discrimination between polioviral and cellular or VSV mRNA could be detected in the mRNP particle.