At the centre: influenza A virus ribonucleoproteins

Influenza A virus has only eight genes, so it is dependent on host proteins and pathways to mediate viral ribonucleoprotein (vRNP) trafficking and to promote vRNP functions at all stages of the virus life cycle. Here, Kawaoka and colleagues describe the trafficking and functions of influenza A vRNPs in host cells, emphasizing how vRNPs interact with and depend on host factors and pathways, how vRNP structure contributes to its function and the key open questions that still need to be answered. Influenza A viral ribonucleoprotein (vRNP) complexes comprise the eight genomic negative-sense RNAs, each of which is bound to multiple copies of the vRNP and a trimeric viral polymerase complex. The influenza virus life cycle centres on the vRNPs, which in turn rely on host cellular processes to carry out functions that are necessary for the successful completion of the virus life cycle. In this Review, we discuss our current knowledge about vRNP trafficking within host cells and the function of these complexes in the context of the virus life cycle, highlighting how structure contributes to function and the crucial interactions with host cell pathways, as well as on the information gaps that remain. An improved understanding of how vRNPs use host cell pathways is essential to identify mechanisms of virus pathogenicity, host adaptation and, ultimately, new targets for antiviral intervention.