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

To identify the mutation that occurred during the cold adaptation of PEDV, the genome of the cold-adapted virus was sequenced and compared to that of the wild-type virus. No additional INDELs were found in the genome after cold adaptation, and the genome size of the Aram-P29-CA strain was determined to be 28,027-nt, which was identical to the parental genome size. Two genetic DEL markers of the Aram strain were also completely conserved in S and ORF3 of the cold-adapted Aram-P29-CA strain (Fig. 2) . The 5′-and 3′-UTRs of the cold-adapted virus remained unchanged, whereas the coding region contained a total of 16 nt substitutions (Fig. 5) . Among these mutations, 12 were non-synonymous, causing changes of 1-aa in nsp3, 1-aa in nsp5, 7-aa in S, 1-aa in E, and 2-aa in M. Details in nt and aa differences between the parental Aram-P5 and cold-adapted P29-CA strains are summarized in Table 2 . Further phylogenetic analysis based on the full-length S and the entire genome indicated that the cold-adapted Aram-P29-CA strain was still clustered into subgroup G2b along with the parental and global epizootic strains (Fig. 3) .