UC San Diego

Influenza A virus (IAV) is a human-infecting pathogen with a history of causing seasonal epidemics and on several occasions worldwide pandemics. Infection by IAV causes a dramatic decrease in host mRNA translation, whereas viral mRNAs are efficiently translated. The IAV mRNAs have a highly conserved 5'-untranslated region (5'UTR) that is rich in adenosine residues. We show that the human polyadenylate binding protein 1 (PABP1) binds to the 5'UTR of the viral mRNAs. The interaction of PABP1 with the viral 5'UTR makes the translation of viral mRNAs more resistant to canonical cap-dependent translation inhibition than model mRNAs. Additionally, PABP1 bound to the viral 5'UTR can recruit eIF4G in an eIF4E-independent manner. These results indicate that PABP1 bound to the viral 5'UTR may promote eIF4E-independent translation initiation.