Degradation of cellular mRNA during influenza virus infection: its possible role in protein synthesis shutoff.

The kinetics of cellular mRNA decay in influenza virus-infected cells have been studied by means of blot hybridization using as probes cloned cDNAs of alpha- and beta-actin, alpha- and beta-tubulin and vimentin. Both cellular mRNAs isolated from the cytoplasmic fractions as well as total cell mRNAs showed a rapid decay, with up to 50% concentration reductions at infection times at which influenza virus M1 mRNA was still not detectable. In contrast, these cellular mRNAs were stable in uninfected cells. To ascertain the possible role of mRNA degradation in the cellular protein synthesis shutoff, the kinetics of protein synthesis in infected cells were examined by two-dimensional gel electrophoresis of extracts pulse-labelled at several times after viral infection. The synthesis of the cellular proteins was reduced, showing kinetics paralleling those of mRNA decay. It is proposed that influenza virus infection induces the destabilization of mRNAs and that this mRNA degradation is, at least in part, responsible for cellular protein synthesis shutoff.