Ultrastructure of influenza virus ribonucleoprotein complexes during viral RNA synthesis

Abstract The single-stranded, negative-sense, viral genomic RNA (vRNA) of influenza A virus is encapsidated by nucleoproteins (NPs) and an polymerase to form a ribonucleoprotein complex (vRNP) with helical, rod-shaped structure. vRNP responsible for transcription replication the vRNA. However, conformation during synthesis not well understood. Here, using high-speed atomic force microscopy cryo-electron microscopy, we investigated native structure vRNPs in vitro. Two distinct types were observed association newly synthesized RNAs: intact, helical connected folded deformed associated looped RNA. Interestingly, was double-stranded RNA, which likely comprises nascent template detached from NPs vRNP. These results suggest that while some keep their structures synthesis, repeated cycle others accidentally become structurally deformed, failure commence or continue synthesis. Thus, our findings provide ultrastructural feature