Three-dimensional reconstruction of a recombinant influenza virus ribonucleoprotein particle

A three-dimensional structural model of an influenza virus ribonucleoprotei n particle reconstituted in vivo from recombinant proteins and a model geno mic vRNA has been generated by electron microscopy. It shows a circular sha pe and contains nine nucleoprotein monomers, two of which are connected wit h the polymerase complex. The nucleoprotein monomers show a curvature that may be responsible for the formation of helical structures in the full-size viral ribonucleoproteins. The monomers show distinct contact boundaries at the two sides of the particle, suggesting that the genomic RNA may be loca ted in association with the nucleoprotein at the base of the ribonucleoprot ein complex. Sections of the three-dimensional model show a trilobular morp hology in the polymerase complex that is consistent with the presence of it s three subunits.