Fig. 1
From: Porcine epidemic diarrhea virus: An emerging and re-emerging epizootic swine virus
Schematic representations of PEDV genome organization and virion structure. a The structure of PEDV genomic RNA. The 5’-capped and 3’-polyadenylated genome of approximately 28 kb is shown at the top. The viral genome is flanked by UTRs and is polycistronic, harboring replicase ORFs 1a and 1b followed by the genes encoding the envelope proteins, the N protein, and the accessory ORF3 protein. S, spike; E, envelope; M, membrane; N, nucleocapsid. Expression of the ORF1a and 1b yields two known polyproteins (pp1a and pp1ab) by −1 programmed RFS, which are co-translationally or post-translationally processed into at least 16 distinct nsps designated nsp1–16 (bottom). PLpro, papain-like cysteine protease; 3CLpro, the main 3C-like cysteine protease; RdRp; RNA-dependent RNA polymerase; Hel, helicase; ExoN, 3’ → 5’ exonuclease; NendoU, nidovirus uridylate-specific endoribonuclease; 2’OMT, ribose-2’-O-methyltransferase. b Model of PEDV structure. The structure of the PEDV virion is illustrated on the left. Inside the virion is the RNA genome associated with the N protein to form a long, helical ribonucleoprotein (RNP) complex. The virus core is enclosed by a lipoprotein envelope, which contains S, E, and M proteins. The predicted molecular sizes of each structural protein are indicated in parentheses. A set of corresponding sg mRNAs (sg mRNA; 2–6), through which canonical structural proteins or nonstructural ORF3 protein are exclusively expressed via a co-terminal discontinuous transcription strategy, are also depicted on the right