Cloning and Sequence Analysis of the Spike Protein Gene of Porcine Epidemic Diarrhea Virus CH/JL Strain and Identification of Its Antigenic Region Containing Linear Epitopes

Three overlapping cDNA clones of the spike gene of porcine epidemic diarrhea virus CH/JL strain was amplified by RT-PCR.Sequence analysis showed that the S gene of CH/JL strain was 96.97%,96.87%,96.41%,94.02% and 93.93% identical at nucleotide sequence level and 96.17%,95.88%,96.10%,92.36% and 92.05% identical at amino acid sequence level to that of strains CV777,Brl/87,JS,KPEDV and Chinju99,respectively.CH/JL strain and JS strain belonged to the same group in the phylogenetic tree based on the nucleotide sequences of the S genes of PEDV strains.An antigenic epitope region of CH/JL strain S protein was predicted by using DNAStar protean software,and was expressed in E.coli BL21(DE3)as a GST fusion protein.Western blotting showed that the fusion protein reacted positively with the polyclonal antibodies against PEDV,suggesting that the predicted antigenic region contained linear antigenic epitopes of PEDV spike protein.