Isolation And Identification Of Canine Parvovirus Sichuan Strains And Studying On VP2 Gene's Varation

Two parvovirus strains were isolated from the feces of 5 dogs from Sichuanregions. The two isolates were designated CPV through a series of systematic identificationassays, such as morphological, physicochemical, biological and molecular virology assay,and so on. Virions are cubical symmetry, about 20-24 nm in diameter, without envelope.These strains can grow in F81 cell line and produce cytopathic effects with thecharacteristics of CPV, swelling, rounding, broken, droping. The strains resist thechloroform treatment and are stable in pH3.0 and 56℃, but are suppressed by 5-IUDR.The viruses can agglutinate RBC of pig, cat, but not of human, chicken, guinea pig. Thepositive antibody against CPV can inhibit HA of these isolates. PCR amplification of the 2strain of virus with special primer of CPV and amplification CPV specific fragment, whatis more, the isolation virus can infect canine. The identification result suggests that the 2strain of virus are both CPV, which are still exist widely in canine population in Sichuanregions of our country.To examine the genotypes of the two CPV isolates, two regions in CPV VP2 gene wereamplified and sequenced. The sequences of these isolates were compared with those of thereference strains for the analysis of specific and important nucleotides by DNAStarsoftware. The results of PCR typing of CPV isolates showed CPV-2a and CPV-2b wereboth present in Sichuan area. The results of cloning and sequencing of VP2 gene showedthe structural protein VP2 contains 1775 nucleotides, encoding 584 amino acids. There is ahigh homology in nucleotide sequence and amino acid sequences. It is nucleic acidhomology over 96% between CPV of Sichuan regions and the other reported referencevirus strain in abroad. It is identical of the mode of evolution with reported literature, but itdoes not come into being obvious a branch of CPV in china. It is first studying from level of molecule in this research and investigating the variation of CPV in western regions ofour country, to better understand the variation and epidemiological status of CPV inSichuan regions and offer useful experiment data for effective prevention.The assay showed that the evolution and variation of CPV in Sichuan aera followed thesame pattern observed in overseas. Phylogenetic analysis of therir complete VP2 sequencesindicated they origined from a common ancestor.