The 30kb positive-stranded RNA genome of coronaviruses encodes a replication/transcription machinery that is unusually complex and composed of 16 nonstructural proteins (nsps). The four proteins nsp7 to nsp10, which are conserved among all CoVs but have no functional homologs outside of the Coronaviridae, are translated as part of the viral polyproteins pp1a and pp1ab, and the mature proteins are released by the action of the SARS-CoV protease nsp5. Hexadecamer of nsp7 and nsp8 may possess dsRNA-binding activity. SARS-CoV 2 nonstructural protein 7 (nsp7) is of interest for its potential roles in the transcription and replication of the positive-stranded viral RNA genome.
