Non-canonical translation of pneumovirus mRNAs

About This Grant

PROJECT ABSTRACT Pneumoviruses, including respiratory syncytial virus (RSV) and human metapneumovirus (HMPV), cause annual epidemics of respiratory infections that can cause serious disease in the young, elderly, and those with co-morbidities. The pneumoviruses are members of the Order Mononegavirales, the non-segmented negative strand RNA viruses. The RNA dependent RNA polymerase of these viruses produces capped and polyadenylated mRNAs resembling those of the host; however, pneumovirus mRNAs face unique challenges in engaging host protein synthesis machinery. Their unusually short 5´ untranslated regions (5´ UTRs) do not provide a sufficient platform for ribosome recruitment through the conventional eIF4E-mediated translation initiation pathway. In our preliminary studies, we have demonstrated that RSV protein synthesis occurs independently of the key translation initiation factor, eIF4E, contrasting with cellular mRNA translation. These findings show that RSV must utilize a non- canonical mechanism of translation initiation. The goal of this project is to identify the viral and cellular factors that enable this non-canonical translation mechanism. We will determine if the 5´ UTRs of pneumoviruses confer the ability to bypass canonical translation pathways and identify which proteins of the cellular translation machinery permit these mRNAs to be efficiently translated. To accomplish this, we will construct reporter viruses to dissect the role of viral 5´ UTRs in promoting this unique mode of translation, and generate auxin-inducible degron-tagged cell lines targeting key eukaryotic initiation factors. Our approach is designed to examine requirements for RSV protein synthesis and define the RSV RNA binding protein (RBP)-ome. We anticipate that this work will provide novel insights into the mechanisms governing pneumovirus mRNA translation and potentially identify targets for antiviral intervention.