Abstract: In order to grasp the prevalence of PEDV in China, a total of 908 clinical diarrhea samples from 160 sites were collected from August 2020 to May 2023,and PEDV antigen detection was performed by qPCR. Some samples were selected for S gene sequencing and analysis,and two prevalent strains of group GⅡ were isolated. The pathogenicity of these two strains was also studied. The results showed that the positive rate of PEDV was 50.7% （460/908） in disease samples and 68.8% （110/160） in pig farms,indicating that a large part of pigs with clinical diarrhea symptoms were caused by PEDV. The analysis of S gene showed that the current prevalence of PEDV in China was mainly in group GⅡ,accounting for 90.3% （65/72） ,while group GⅠ showed sporadic incidence,accounting for 9.7% （7/72） . Two viral strains of Group GⅡ were successfully isolated and obtained,both of which had pathogenicity to fattening pigs of 3-4 months of age. The experimental pigs were attacked orally,33%-67% of the pigs could have diarrhea,100% of the experimental pigs were infected and sustained detoxification,and the longest detoxification time could reach 13 days after the challenge. The epidemiology,genetic variation and pathogenicity of PEDV were studied in this study,which provided a basis for disease prevention and control and product development.

Key words: porcine epidemic diarrhea virus (PEDV), S gene, virus isolation, virulence