| Feline Panleukopenia(FP)is an acute infectious disease caused by Feline panleukopenia virus(FPV)with high mortality and high contact.It is usually accompanied by high fever,vomiting,diarrhea,dehydration,and a sharp decline in white blood cell count.Feline Panleukopenia is also known as feline distemper,feline parvovirus infection,feline infectious enteritis.FPV has a wide host spectrum,it can infect almost all felids,weasels and raccoons.FPV causes a high mortality rate of cats,minks,raccoons and other animals,and FPV seriously affects the health of large wild cats in China,such as snow leopards and Amur tigerse in recent years.At present,China is second to the United States in raising pet dogs and cats,and the number of dogs and cats ranks the second in the world.In 2021,the number of cats in China’s cities was 52.62 million.The prevention of FP relies on imported vaccines.At present,only Miaosando(inactivated feline triplet vaccine)is available in China.Due to the shortage of cat vaccines in China due to the impact of COVID-19,the development of domestic cat vaccines is urgent.The epidemiological investigation of feline panleukopenia virus in China is limited.This study focused on the prevalence,molecular biological characteristics and genetic variation of FP in domestic cats in Zhengzhou,Luoyang and Luohe of Henan Province,which is of great significance for the prevention,diagnosis and treatment of FPV as well as the development of new vaccines.In this study,a total of 1221 samples were collected from pet hospitals and cat houses in Zhengzhou,Luoyang and Luohe of Henan province from January to December 2021.FPV PCR was used to identify the samples,and the results showed the positive rate of FPV was 13.02%,including 12.16%(40/329)in Zhengzhou,14.44%(26/187)in Luoyang,and 13.19%(93/705)in Luohe.FPV infection in cats was seasonal,and the infection rate of FPV was high in winter and spring,ranging from 15.49% to 17.18%.Unvaccinated kittens are more susceptible to FPV,and some vaccinated cats can still test positive for FPV.In this study,11 FPV positive samples were selected for whole-genome sequencing randomly,and their VP2 gene and NS1 gene were sequenced.Similarity analysis results based on VP2 gene showed that the similarity between VP2 gene of 11 samples and VP2 gene of FPV strains was 98.8%-99.8%,and the similarity between VP2 gene of CPV strains was 97.6%-99.0%.Similarity analysis results based on NS1 gene showed that the similarity between NS1 gene of 11 samples and NS1 gene of FPV strains was 98.9%-100%,and the similarity between NS1 gene of CPV strains was 98.4%-99.5%.The results showed that VP2 and NS1 genes were conserved between FPV strains,between FPV strains and CPV strains.The 11 FPV positive samples were not in the same genetic evolutionary branch with FPV and CPV vaccine strains,and their similarity was not high.The results of this study questioned the protective efficacy of FPV vaccine against the epidemic strains in China,suggesting that the immunoefficacy of current commercial FPV vaccine should be evaluated.The FPV vaccine should be developed as soon as possible for the virus strains circulating in China.The virus was isolated by inoculating f81 cells with 20 samples whose PCR results were pure FPV positive.11 samples showed CPE(cytopathy)during cell passage,such as rounding,shrinkage,shedding and wire drawing.The 11 cell cultures were identified and verified by PCR,electron microscope observation,immunofluorescence assay(IFA)and virus content titration.The results showed that the 11 isolates were FPV.In the animal regression experiment,the strain fpv27 with the highest titration value of virus content was selected for animal regression experiment.In the experiment,the animals had symptoms such as high fever,loss of appetite,vomiting,diarrhea,dehydration,bloody stool and death,and the mortality was 100%.The results showed that fpv27 strain was a strong strain with high pathogenicity and lethality to cats. |
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