Differences in RNA Binding Between Segmented and Non-Segmented Negative-Strand Virus Nucleocapsids

Segmented and non-segmented negative-strand RNA viruses share the same general pathway for genome transcription, which generates messenger RNA, and genome replication which duplicates the viral RNA. These processes are performed by the viral polymerase and necessitate the viral RNA to be coated by a non-covalent polymer of nucleoproteins known as nucleocapsid. The non-segmented negative-strand RNA viruses (nsNSVs) have rigid nucleocapsids covering the entire tightly bound genome and require a phosphoprotein cofactor for proper replication and transcription by the polymerase, while the segmented negative-strand RNA viruses (sNSVs) have very flexible nucleocapsids with only few nucleotides tightly bound to each nucleoprotein, and their viral RNA genome ends are directly bound to the polymerase. We discuss here how the differences in RNA binding are likely to be crucial for proper replication and transcription in both nsNSVs and sNSVs.