| Mink enteritis virus (MEV) causes a highly contagious viral disease of mink with a worldwide distribution. MEV has a linear, single-stranded, negative-sense DNA with a genome length of approximately 5,000 bp. The VP2 protein is the major structural protein of the parvovirus encoded by the vp2 gene. VP2 is highly antigenic and plays important roles in determining viral host ranges and tissue tropisms. In this study, MEV strains were isolated in DaLian and Changchun in China. All strains can accumulation in cell culture normally and cause cytopathic effection. hemagglutination test was used to identification of MEVstrain. Results showed that the MEV strains can agglutinate pig erythrocyte. PCR showed a fragment with a length of 1999bp when observed through agarose gel electrophoresis. MEV particles electronmicroscopic about 20nm. Comparative analysis of MEV strains'nucleotide sequences of VP2 gene showed its more than 99% homology with other mink enteritis parvoviruses. However, a new MEV strain have been found which have some changes in VP2 protein and may be have impact on it's antigenicity.Feline parvovirus sub-species include feline parvovirus (FPV), canine parvovirus (CPV), blue fox parvovirus (BFPV), raccoon parvovirus (RPV), raccoon dog parvovirus (RDV) and so on. These viruses are single-stranded DNA virus. Previous studies suggested that CPV may derive from one of feline parvovirus sub-species, but most of studies believed that CPV originated from FPV, considering that FPV was the ancestor of other members of feline parvovirus sub-species. Little difference of vp2 nucleotide and VP2 protein exist among members of feline parvovirus sub-species, which however result in the virus infecting new host or having a change in cell tropism. Among the feline parvovirus sub-species, CPV showed a high level of the average nucleotide (nt) substitution rate of 1.68X10-4 per site per year higher than MEV and FPV which had the mean substitution rates were 7.85X10-5 and 2.95X10-5 per site per year, respectively. The nt substitution of MEV was 7.85X10-5 higher than FPV but lower than CPV analysis through Bayesian Markov chain Monte Carlo ( MCMC )method based on the vp2 gene sequence deposited in Genbank from 1988 to 2009. Population dynamic analysis showed that: variability of population density of CPV and MEV higher than FPV. VP2 protein is the major structural protein, and determine capacity of virus adsorb to cells. In this paper, VP2 protein sequence of various feline parvovirus sub-species isolation strain in different host were collected from Genbank . and the result showed that most of the mutatant position located in the vicinity of loop1 and loop3, also most of mutations result in replacement of amino acids from the hydrophilic amino acids to acidic amino acid or hydrophobic amino acid, in which the position of 300 in VP2 protein is the most abundant amino acid mutations position. Recombinant between MEV and FPV was revealed by analyzing the genetic data deposited in databases with RDP recombination detection program. CPV formed one clade while other feline parvovirus sub-species formed another clade by phylogeny. MEV and FPV also be separated by various clades.MEV were high variability, and genetic difference of vp2 gene among the MEV strains which isolated in 2007, 2008 and 2009 and vaccine strains on the market had been analyzed to chose the MEV strain for immue the horse, then IgG was purified from serum for the further study of treatment experiment. |
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