Generation and protective efficacy of a cold-adapted attenuated genotype 2b porcine epidemic diarrhea virus

Won, Hokeun; Lee, Dong-Uk; Jang, Guehwan; Noh, Yun-Hee; Lee, Seung-Chul; Choi, Hwan-Won; Yoon, In-Joong; Yoo, Han Sang; Lee, Changhee

Porcine epidemic diarrhea virus (PEDV) is a member of the genus Alphacoronavirus, belonging to in the family Coronaviridae of the order Nidovirales. PEDV is a large, enveloped virus possessing a 5′ capped, single-stranded positive-sense RNA genome of approximately 28 kb, with a 3′ polyadenylated tail [1, 2] . The PEDV genome consists of seven canonical genes, including an open reading frame (ORF) 3, flanked by 5′-and 3′-untranslated region (UTRs). The first two large ORFs comprise two-thirds of the genome and encode the replicase polyproteins, 1a and 1ab, which are then posttranslationally cleaved into 16 mature non-structural proteins (nsp1-16). The last one-third encodes four canonical coronavirus structural proteins in a fixed order, spike (S), membrane (M), envelope (E), and nucleocapsid (N), as well as a single accessory gene encoding ORF3 between S and M [1] [2] [3] . The virus can be phylogenetically divided into two genotypes comprising two sub-genotypes: genogroup 1 (classical G1a and recombinant G1b) with low-pathogenicity, and genogroup 2 (local epidemic G2a and global epidemic or pandemic G2b) with high-pathogenicity [1, 2, [4] [5] [6] .