Studying On Generations And Evolution Of Vp2 Gene Of Canine Parvovirus And Feline Parvovirus Isolated Strains

Carnivorous parvovirus belongs to parvoviridae of parvovirus.There are many kinds of animals are susceptible to Carnivorous parvovirus in the world. Not only domesticated animals but also wild animals are infected by Carnivorous parvovirus in China. Among Carnivorous parvovirus,FPV is one of main infectious diseases pathogen to domesticated animals ,wild animals and economic animals of fenine, raccoon,mustela animals.Because of the many infected animals, the strong pathogenicity and high fatality rate,it is a big threaten to the breed police dog, pet dog, domesticated dog. So more and more researchers pay attention to it.Its'VP2 gene decides the viruses'host rang,HA property and antigenicity.The fast evolution of Carnivorous parvovirus gene depends on the mutation of some important amino acid residue and adapting to host fast.Comparison of the published sequences of FPV,CPV,MEV VP2 on Genbank, a pair of specific primer targeting to the common conserved sequence was designed. Eighteen CPV positive samples were identified from thirty canine enteritis samples from different time and different region in China from 2007-2008 and nine CPV strains were isolated. Ten FPV positive samples were identified through twenty samples, seven FPV strains were isolated. The isolated strains were further identified through cell culture,morphological, physicochemical, biological and molecular virology assays.The VP2 gene was amplified with designed CPV and FPV specific primer and analyzed by sequencing.Through animals test, we found that all of the dogs were infected by isolated CPV strains, and all the dogs infected by CPV-CN-5 strain died.The results of PCR showed that Parvovirus positive rate is relative high in China.We infered that the CPV and FPV prevail in China.These strains could grow in F81 cell and produce cytopathic effects.The strains show the properties of Carnivorous parvovirus.And some dogs died from infecting of CPV-CN-5 isolated strain.A virulent strain was screened by animals test,which provided some experimental data to prevent and cure canine parvovirus disease effectively.The sequence analysis to the whole VP2 gene showed that the full length of VP2 gene of isolated strains is 1755 bp, which encodes 584 amino acids, with the same length as the VP2 gene of standard strain. The homology of nucleotide among seven FPV isolated strains were 99.93%.The homology of amino acid sequences were 99.8%.Compared with the standard strains,the homology of nucleotide and amino acid sequences between the seven FPV isolated strains were 99.62% and 99.75%.The homology of nucleotide and amino acid sequences among nine CPV isolated strains were 99.41% and 99.05%.The homology of nucleotide between the nine CPV isolated strains and the standard strains were from 99.40% to 99. 44% and the homology of amino acid sequences were from 98.99% to 99.14%. Phylogenic tree based on VP2 genes showed that different strains of FPV clustered into the previous genotype. It's evolution was similar to the documents, that there were some variation in VP2 gene, most variations were synonymous mutation rather than the missense mutation. But different strains of CPV clustered into a new genotype.Six CPV strains of nine isolated strains belong to CPV-2a, and the another three strains are mutates.The animals test result showed that CPV-CN-5 is a velogenic strain. This study clarifies the molecular characteristics of genetic variation of strains of FPV and CPV.This study provided some experimental data to the further understand of the evolution and variation of CPV and FPV in China.The heredity and evolution analysis of VP2 gene of CPV and FPV isolated strains provided some test datas for preventing and curing canine parvovirus disease effectively.