Molecular Epidemiological Investigation Of Porcine Epidemic Diarrhea Virus And Genetic Analysis Of Porcine Epidemic Diarrhea Virus SH Strain

To investigate the molecular epidemiological characteristics of PEDV epidemic strains in China in recent years,in this study,80 samples were collected from different provinces in central and eastern China during 2018 for PEDV detecting.S gene,N gene and ORF3 gene in 13 positive samples were sequenced and analyzed.To investigate the stability of PEDV SH strain isolated before on Vero cells,the virus were passaged on Vero cells.Every 20 generations,The cytopathic effect,TCID50 and the growth curve were detected,and the S gene,N gene and ORF3 gene were sequenced and analyzed.This study provided epidemiological data for the control of PEDV and laid the foundation for the cultivation of attenuated strains of PEDV.The specific research contents are as follows:1.Molecular epidemiological investigation of porcine epidemic diarrhea virus in central and eastern China in 2018To investigate the molecular epidemiological characteristics of PEDV epidemic strains in central and eastern China in recent years,in this study,80 samples were collected from 22 pig farms in 2018 for PEDV detecting.S gene,N gene and ORF3 gene of 13 positive samples were sequenced and compared with 42 reference sequences.The results showed that 35 of the 80 samples were positive,with a positive rate of 43.75%.7 S gene sequences,13 N gene sequences and 12 ORF3 gene sequences were obtained.S gene analysis showed that all the 7 strains belonged to the G2 group.The analysis results of N gene and ORF3 gene showed that these strains were closely related to the epidemic strains.Amino acid sequence analysis showed that the S protein of the 7 strains had the signature amino acid insertions and deletions of the epidemic strains,and there were new mutations.There were mutations in amino acid sequence of N protein and ORF3 protein,but no insertions or deletions.The results also showed that 13 strains were endemic strains.2.Genetic analysis of porcine epidemic diarrhea virus SH strainTo obtain the attenuated strain of PEDV,in this study,PEDV SH strain isolated before was passaged on Vero cells.Every 20 generations,the cytopathic effects were compared,TCID50 was determined,and the growth curve was drawn,and the S gene,N gene and ORF3 gene were sequenced and analyzed.The results showed that SH strain gradually adapted to Vero cells during passage,the proliferation was faster and the titer of virus was higher.During passage,12 base mutations and 6 amino acid mutations occurred in S gene,6 base mutations and 5 amino acid mutations occurred in N gene,Neither had any insertion or deletion.ORF3 gene had no mutation and was conservatively inherited.