Fig. 5.
Genome organization of members in Beta‐, Alpha‐ and Deltacoronavirus genera. The genomic viral genomes are single‐stranded, positive‐sense RNA with a 5′ m7G‐cap (black circle) and a poly‐A tail (A30‐60) at the 3′ end. The genome encodes 16 non‐structural proteins (ORF1a: nsp1‐11 and ORF1b: nsp12‐16), 4 structural proteins (S, spike; E, envelope; M, membrane; N, nucleocapsid) and a varying number of accessory proteins (numbered boxes or ns). The upper 6 genomes are infectious for humans and are responsible for severe pathologies (SARS‐CoV‐2 and MERS‐CoV) or common pathologies (colds) (HCoV‐OC43, ‐HKU1, ‐229E, ‐NL63). HCoV‐OC43 and ‐HKU1 are characterized by a fifth structural protein: HE (hemagglutinin‐esterase). Infectious bronchitis virus (IBV) and Porcine CoV HKU15 are Gammacoronaviruses and Deltacoronavirus, respectively. They lack NSP1 protein and are among the smallest viruses in coronaviridae.