Research On The Isolation And Biological Characteristics Of Feline Panleukopenia Virus XJ Strain

In this study, the virus in the feces specimens from the intestine of the cat in Xinjiang province were collected and proliferated on CRFK. The titer of Tissue culture infective dose (TCID50) of the third generation cell cultures was 104.21. The typical appearance of parvovirus with the real and aircored particles was oberseved under electron microscope. The distinctive fluorescence was found after the culturing medium was recognized by the McAb (monoclonal-antibody) of FPLV. The cats of two months old were infected and died in the seventh day after inoculated the culturing medium. The inoculated cats appeared the specific pathological symptoms of infection by FPLV. The VP2 gene of the virus was amplifyied by PCR and was consistent with FPLV. The isolated virus was named FPLV-XJ.Under the condition of 4℃, The culturing medium can agglutinate the red blood of pigs and the agglutination was inhibitied by the FPLV McAb. The titer of Hemagglutination of FPLV-XJ was 512. While, the culturing medium cannot agglutinate the red blood of rabbits, chooks, dogs and KunMing mice. The FPLV-XJ proliferated in the MDCK, but not in Hela, Vero, DF-1 and PK-15. The cultivation characteristic of the virus proliferated in the CRFK oberseved by IFA 24 hours interval was that the virus was released from CRFK in the 6th day after quickly multiplicatied for 5 days by synchronal inoculation. The PCR products of VP2 and NS1 gene were amplifyied and sequenced. The result shows that the full-length VP2 gene contained 1755bp which encodes 584 amino acids. The nucleotide identity of VP2 genes between the FPLV-XJ strain and 4 CPV strains and 5 strains FPLV in the GenBank was more than 99% by the sequencing analysis. Correspondingly, the amino acid identity was 98.5%~99.7%. VP2 gene of the FPLV-XJ strains didin't change remarkably. For NS1 gene, it contained 2007bp which encodes 668 amino acids. Homologies of nucleotide and amino acids sequences of the NS1 gene between FPLV-XJ and 5 CPV strains and 6 FPLV strains was 98.7%~99.3% and 98.5%~99.3%. Phylogenetic analysis of NS1 gene show that the relation between the FPLV-XJ strain and CPV-b was closer. The results indicated that the NS1 gene of the FPLV-XJ Strain had variated. The FPLV-XJ strain may be intergradation from FPLV to CPV after FPLV was transmitted in intermediate host.This study on the isolation and biological characteristic of the FPLV-XJ strain from XinJiang by morphology, serology, histopathology and molecular biology provides informantion and data for Pathogen, Pathopoiesis, Epidemiology of FPLV. In addtion, it offered an evidence about the evolution of CPV.