Molecular Epidemiology Investigation And Isolation Of Porcine Epidemic Diarrhea Virus S1 Gene In China From 2015 To 2016

Porcine epidemic diarrhea virus,as a main etiological agent responsible for porcine viral diarrhea.A large number of epidemiological data show that PEDV virulence mainly depends on the S1 gene mutation.The insertion deletion mutation of S1 protein plays an important role in the pathogenicity and tissue tropism of virus.Therefore,molecular epidemiological investigation of S1 gene and isolation of representative variant strains is benefit to elucidate the genetic evolution of PEDV and provide basic information.To understand the genetic evolution of PEDV in China from 2015 to 2016.Intestinal tissues samples were collected from the diseased piglets of 78 farms in 20 provinces or municipalities.All samples were detected by RT-PCR based on ORF3 gene.Then the S1 gene of PEDV positive samples was amplified and sequenced.The S1 genes of PEDV strains identified were subjected to the analysis of phylogeny,insertions and deletions mutation pattern of S1 protein?S1-IDMP?,homology modeling of protein,and recombination.The result showed that 243 PEDV positive samples,a total of 97 S1 genes were successfully sequenced,covering 18 provinces or municipalities of China.Sequence analysis indicated 95.9¹00% nucleotide identity and95.9¹00% amino acid identity;the 97 identified S1 genes exhibited 91.6⁹2.8% nucleotide sequence homologies and 89.5⁹1.3% amino acids homologies when compared with PEDV CV777 strain.Phylogenetic analysis revealed that the PEDV strains identified in our study belonged to the pandemic PEDV strains?G ??,and showed genetic diversities and potential recombination.Analysis of insertions and deletions mutation pattern of S1 protein indicated that the^INQ⁵⁹GVN—^INN¹³⁶—^DELD¹⁵⁸I or S1-IDMPs similar to^INQ⁵⁹GVN—^INN¹³⁶—^DELD¹⁵⁸I were pandemic insertions and deletions mutation pattern in both identified strains and Chinese PEDV pandemic strains?91.1%,450/494?;the^INQ⁵⁹GVN—^INN¹³⁶—^DELD¹⁵⁸I—^DELN⁵⁵³VTNSYGY of the LN/DT/2016/510 a strain was an unique novel S1-IDMP of PEDV in China,and the ^DELN⁵⁵³ VTNSYGY mutation caused changes of the central structure of S1-RBD for receptor binding of PEDV.Furthermore,LN/DT/2016/510 a strain was revealed to be one recombinant strain generated by two PEDV pandemic strains with the S1-IDMP^INQ⁵⁹GVN—^INN¹³⁶—^DELD¹⁵⁸I.PEDV-HM2017 strains were successful isolated through blind passages in Vero cell.The S1 gene of phylogenetic analysis revealed that PEDV-HM2017 strain has a closely relationship withChinese prevalent strains.This study identified the genetic evolution and S1-IDMPs of PEDV S1 gene from 2015 to2016.The successful isolation of PEDV-HM2017 strains will provide the basic information for PEDV strains in China.