Structure and mechanism of translation initiation in picornavirus infection (360G-Wellcome-338898_Z_25_Z)

Picornaviruses cause approximately one billion infections annually, leading to diseases ranging from the common cold to meningitis and myelitis. Their extensive genetic diversity has hampered antiviral drug development, but all picornaviruses share a critical dependence on the host translation machinery. Exploiting this vulnerability requires a detailed understanding of viral translation initiation, therefore this proposal investigates how picornaviruses hijack ribosomes via internal ribosome entry sites (IRESs). By comparing initiation mechanisms across Type 1, 2 and 5 IRESs, we aim to define conserved structural and mechanistic features for targeting by new broad- spectrum antivirals. Aim 1 will determine high-resolution cryo-EM structures of initiating ribosomes, both in vitro and in virus-infected cells, revealing the atomic details of interactions between IRES elements, initiation factors, ribosomal subunits and RNA-binding proteins. Aim 2 will apply TIRF microscopy to track initiation on single IRES molecules, monitoring the real-time recruitment of initiation factors and ribosomal subunits to establish the sequence and interdependence of assembly events. Aim 3 will evaluate different inhibition strategies, by designing peptides that block IRES contact sites on the ribosome, and screening for RNA-binding compounds targeting structured IRES domains. Together, these studies will provide fundamental insights into translational control, and lay foundations for developing novel antivirals.