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Isolation and genetic analysis of a variant porcine epidemic diarrhea virus in China

Li, Ren-feng, Tian, Xiang-qin, Liu, Yong, Xu, Jing, Liu, Dong-yang
Polish journal of veterinary sciences 2016 v.19 no.1 pp. 65-73
Porcine epidemic diarrhea virus, diarrhea, electron microscopy, epidemiology, fluorescent antibody technique, genes, genetic analysis, industry, livestock breeding, mucosa, neonates, phylogeny, piglets, reverse transcriptase polymerase chain reaction, small intestine, vaccines, China
Porcine epidemic diarrhea virus (PEDV) is having a severe effect on the pig breeding industry in central China. The mucosa and the content of the small intestine from newborn pre-weaned piglets with diarrhea were tested for the presence of PEDV by molecular and morphologic methods, and found to be positive. Negative-staining electron microscopy (EM) revealed the presence of coronavirus- like particles in the samples. The result of molecular detection by nested RT-PCR based on the amplification of the M gene was positive. Using a novel alternative method we successfully propagated the PEDV strain (CH/QX-2) in Vero cells, confirmed by ultrathin sections of the cells and Immunofluorescence assay (IFA). Phylogenetic analysis based on the partial S gene showed that the CH/QX-2 isolate was genetically closer to strains more commonly found in China, but differed genetically from two domestic strains (CH/S, 1986 and LZC, 2007), Korean strains (DR13, 2007), and the vaccine strain (CV777 vs) currently being used in China. CH/QX-2 formed a unique clade in the derived phylogenetic tree indicating that the CH/QX-2 strain currently circulating in central China is a new variant of PEDV. This study extends current knowledge on the diversity and epidemiology of PEDV.