Figure 2.

The genomic organization of SARS-CoV-2 (strain WH-Human 1 CoV) and representative animal coronaviruses (CoVs). The replicase gene constitutes two-thirds of the CoV genome, and consists of two overlapping open reading frames (ORFs), ORF 1a and 1b, which are translated into two large polypeptides, pp1a and pp1ab. The remaining 3′- region of the CoV genome (expanded in the figure) encodes the structural (spike (S), envelope (E), membrane (M), nucleocapsid (N)) and accessory proteins (highlighted with green boxes). The size of the complete genome of CoV is shown in parenthesis. ¹ A large deletion (~600 nt at 5′- end) in the S gene transformed TGEV into PRCoV. Abbreviations: BCoV—bovine coronavirus; CCoV—canine coronavirus; CoV—coronavirus; FCoV—feline coronavirus; E—envelope; IBV—infectious bronchitis virus; M—membrane; MHV—mouse hepatitis virus; N—nucleocapsid; nt—nucleotide; ORF—open reading frame; PDCoV—porcine deltacoronavirus; PEDV—porcine epidemic diarrhea virus; PRCoV—porcine respiratory coronavirus; SADS-CoV—swine acute diarrhea syndrome coronavirus; S—spike; TGEV—transmissible gastroenteritis virus.