Inhibition of translation by poliovirus: inactivation of a specific initiation factor.

TLDR

Poliovirus infection blocks translation of VSV mRNA, mirroring the inhibition of host mRNA translation. The study aimed to elucidate the mechanism by which poliovirus suppresses protein synthesis. Researchers prepared extracts from infected and uninfected HeLa cells, added purified initiation factors, and mixed extracts to pinpoint the inhibitory factor. They found that poliovirus infection selectively inactivates eIF‑4B, allowing poliovirus mRNA to be translated but preventing VSV mRNA translation.

Abstract

Translation of vesicular stomatitis virus (VSV) mRNA, like host mRNA translation, is inhibited in cells infected with poliovirus. To study the mechanism of poliovirus-induced inhibition of protein synthesis, we prepared extracts from poliovirus-infected and uninfected HeLa cells. Poliovirus mRNA was translated in lysates from both infected and uninfected cells, while VSV mRNA was translated only in the lysate from uninfected cells. Addition of purified translation initiation factors to the extract from infected cells showed that one factor, eIF-4B, could restore VSV mRNA translation in the infected lysate, but did not increase poliovirus mRNA translation. Further experiments involving translation of VSV mRNA in mixed extracts from poliovirus-infected and uninfected cells showed (i) that there was not an excess of an inhibitor of VSV mRNA translation in the infected lysate, but (ii) that an acitivity that caused a slow inactivation of eIF-4B was present in the infected lysate. Inactivation of eIF-4B appears to be the mechanism by which poliovirus infection causes a selective inhibition of translation.