CORONAVIRAL GENOME STRUCTURE AND REPLICATION

CoVs belong to the subfamily Coronavirinae in the family of Coronaviridae of the order Nidovirales, and this subfamily includes four genera: Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus. The genome of CoVs is a single-stranded positive-sense RNA (+ssRNA) (∼30kb) with 5′-cap structure and 3′-poly-A tail. The genomic RNA is used as template to directly translate polyprotein 1a/1b (pp1a/pp1ab), which encodes non-structural proteins (nsps) to form the replication-transcription complex (RTC) in a double-membrane vesicles (DMVs).