Isolation And Identification Of Yanji Strain Of Feline Parvovirus And Its Molecular Epidemiological Investigation

Feline parvovirus belongs to the family parvovirus and can cause Feline parvovirus disease,a highly contactable,acute infectious disease common in cats and felines,with high morbidity and mortality.Due to the lack of effective treatment for FPV infection and the possibility of sequelae after cure,the main focus is on prevention and early vaccination,which has occurred in recent years due to mutations in FPV,resulting in weakened or ineffective vaccines.Since Yanji is located at the border of Jilin Province,there are close exchanges with neighboring countries,and there are no investigations and studies on the molecular epidemiology of FPV within Yanji,it is important to isolate local virus strains and take rapid and targeted measures for the prevention and treatment of feline parvovirus disease.In this study,we will isolate the Yanji strain of FPV,analyze the full gene sequence mutation of the isolate VP2,and conduct a molecular epidemiological survey of FPV-infected cats in Yanji to understand the current epidemiological trend and status of FPV in Yanji,so as to provide a certain data guarantee and theoretical basis for the subsequent in-depth study of the prevalence of FPV and the prevention and treatment of feline parvovirus in Yanbian Prefecture and the northeast region.Isolation and identification of Yanji strain of FPV.A clinical sample of suspected FPV infection from Yanji Animal Hospital was collected and initially identified as positive for FPV by PCR,and the viral solution was extracted and inoculated into F81cells blinded to the 5th generation,and obvious cytopathic（CPE）phenomenon appeared after 48 h of culture,and typical FPV virus particles were visible under electron microscopy,with a diameter of about 20-24 nm and a virus titer TCID₅₀of1×10^-4.94/m L The whole gene sequence of the isolated strain VP2 was amplified and compared with the key amino acid sites that determine the host range and antigenic specificity of the virus,and the results showed a perfect match with the standard strain of FPV（Gen Bank accession number:M38246）.It proved that a strain of FPV was successfully isolated in Yanji City and named YBYJ-1 strain FPV（Gen Bank accession number:OM212011）.The molecular epidemiological survey of FPV in Yanji city.100 clinical samples of suspected FPV infection were collected in Yanji city between 2021 and 2022,and the positive samples identified by PCR were molecularly cloned and sequenced to obtain a total of 27 FPV VP2 full gene sequences including the above YBYJ-1 strain（uploaded to Gen Bank）,so the detection rate of FPV in this survey was 27%.The analysis results showed that the amino acid homology among the 27 FPV strains was maintained at 98.3%-99.8%,and the amino acid homology was maintained at95.7%-100%when compared with 24 reference strains at home and abroad,which showed that the 27 FPV strains did not have large mutations.The analysis of FPV genetic distance and mutations at key amino acid loci showed that the prevalent strains of FPV in Yanji were mainly in the G3 group and a few in the G2 group.In this study,a strain of FPV G3 group with a viral titer TCID₅₀of 1×10^-4.94/m L was successfully isolated from Yanji city and named as YBYJ-1 strain of FPV（Gen Bank accession number:OM212011）.A total of 27 strains of FPV VP2 full gene sequences were obtained from 100 samples of suspected FPV infection in Yanji city,and the molecular epidemiological investigation and analysis showed that the prevalence of FPV in Yanji city was dominated by the G3 group.This is the first molecular epidemiological survey on FPV in Yanji,which will lay the foundation for the research on the pathogenesis of FPV and the development of vaccine.