Isolation,Identification Of Feline Panleukopenia Virus And Prokaryotic Expression Of The Dominant Antigentic Region Of VP2 Protein

Feline panleukopenia(FP)is a highly contacted infectious disease caused by feline panleukopenia virus(FPV),and is characterized by severe reduction of white blood cells and hemorrhagic enteritis.The disease is prevalent worldwide,posing a great threat to the breeding of cats and the protection of wildlife.FPV is a non-enveloped single-stranded DNA virus.The genome of FPV contains hairpin structures.The middle part encodes two kinds of proteins: non-structural proteins(NS1,NS2)and structural proteins(VP1,VP2).The NS1 protein is involved in viral replication,and the structural VP2 protein has six key amino acid positions that determine the host range of the virus and its antigenicity.In this study,FPV BJ04 strain was isolated,and its biological characteristics,genomic analysis and prokaryotic expression of the fragment of VP2 were carried out,which laid a foundation for studying the epidemic variation of FPV strains in Beijing.In this study,a fecal sample suspected FPV-infected cat was collected from an animal hospital,and the test was performed using the FPV colloidal gold test strip.The test result was strongly positive.The virus was isolated and cultured by CRFK cell passage,and after 5 generations of blind passage,significant cytopathic effects were produced on CRFK cells.After indirect immunofluorescence test,morphological observation of virus and related molecular biology,it was identified as FPV and named as FPV BJ04.After animal regression tests,the strain can cause typical clinical symptoms and histopathological changes in cats.By cloning the whole genome of the virus,DNAstar software was used to analyze the homology of VP2 gene of FPV BJ04 and other FPV strains,CPV strains and MEV strains on GenBank.The nucleotide homology between BJ04 and the reference strains reached 98.3% ~99.9%,and the amino acid homology reached 97.3% ~ 100%.The NS1 gene of BJ04 was compared with the sequences of the FPV strain,CPV strain and MEV strain registered on GenBank,and the nucleotide homology was 98.5% ~ 99.9%,the amino acid homology was 98.1% ~ 99.9%.The bioinformatic software was used to predict the epitope of VP2 protein of FPV BJ04 strain,and the 307 ~ 408 amino acids on VP2 protein was identified as the dominant antigen region,and the gene in this region was prokaryotic expression.Western blot analysis showed that the expressed recombinant protein had reactogenicity,which laid a foundation for studying of the interaction between different domains of VP2 protein and host.