The Israeli Acute Paralysis Virus IRES captures host ribosomes by mimicking a ribosomal state with hybrid tRNAs.

The Colony Collapse Disorder or CCD is a multi-faceted syndrome decimating bee populations worldwide. A group of viruses of the widely distributed Dicistroviridae family have been identified as a causing agent of CCD. This family of viruses employ non-coding RNA sequences, called Internal Ribosomal Entry Site (IRES), to precisely exploit the host machinery for protein production. Using single-particle cryo-electron microscopy (cryo-EM) we have characterized at high resolution how the IRES of the intergenic region of the Israeli Acute Paralysis Virus (IAPV) captures and redirects translating ribosomes towards viral messengers. Through a series of six structures at nominal resolutions close to 3A, we could reconstruct the trajectory of IAPV-IRES from an early small subunit recruitment to a final post-translocated state in the ribosome. An early commitment of IRES/ribosome complexes for global pre-translocation mimicry explains the high efficiency observed for this IRES. The presented structures will help guide on-going efforts directed towards fighting CCD through RNA-interference technology.