Analysis of the vp2 gene sequence of a new mutated mink enteritis parvovirus strain in PR China

Abstract

Background: 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. This study describes the bionomics and vp2 gene analysis of a mutated strain, MEV-DL, which was isolated recently in China and outlines its homologous relationships with other selected strains registered in Genbank.

Results: The MEV-DL strain can infect F81 cells with cytopathic effects. Pig erythrocytes were agglutinated by the MEV-DL strain. The generation of MEV-DL in F81 cells could infect mink within three months and cause a disease that was similar to that caused by wild-type MEV. A comparative analysis of the vp2 gene nucleotide (nt) sequence of MEV-DL showed that this was more than 99% homologous with other mink enteritis parvoviruses in Genbank. However, the nucleotide residues at positions 1,065 and 1,238 in the MEV-DL strain of the vp2 gene differed from those of all the other MEV strains described previously. It is noteworthy that the mutation at the nucleotide residues position 1,238 led to Asp/Gly replacement. This may lead to structural changes. A phylogenetic tree and sequence distance table were obtained, which showed that the MEV-DL and ZYL-1 strains had the closest inheritance distance.

Conclusions: A new variation of the vp2 gene exists in the MEV-DL strain, which may lead to structural changes of the VP2 protein. Phylogenetic analysis showed that MEV-DL may originate from the ZYL-1 strain in DaLian.

Figure 1

Divergence and percentage identity of nucleotide sequence variations in the VP2 gene among the nine MEV strains. a) The VP2 gene sequence of the ZYL-1 strain isolated from DaLian in China (accession number: GU272028) have a homology of up to 99.9% while the ZYT-2 isolation strain (accession number: FJ712221) have a homology of 99.2% when compared with MEV-DL. b) The accession number of the MEV strains shown above are as follows: MEV-e (U22191), Abashiri (D00765), Beregovoi-Biocentr (AY665656), Suning (FJ712217), LYT-2 (FJ712221), ZYL-1 (GU272028), Mink enteritis virus (M23999), Rodniki-Biocentr (AY665657), and MEV-DL (HM015824).

Figure 2

Phylogenetic analysis based on the complete VP2 nucleotide sequences of different parvovirus isolates. Nucleotide sequences showed that our MEV-DL isolate was similar to the ZYL-1 and Suning isolates. The sequences of the VP2 genes were obtained from the GenBank. The accession numbers were as follows: MEV-e (U22191), Abashiri (D00765), ZYL-1 (GU272028), MEV-DL (HM015824), Suning (FJ712217), LYT-2 (FJ712221), Beregovoi-Biocentr (AY665656), Rodniki-Biocentr (AY665657), Mink enteritis virus (M23999), 389/07 (EU145593), 933/07 (EU360958), ChangC2007 (FJ936171), 04S23 (DQ025992), K029 (EU009205), 128/08 (FJ005246), GR51/08 (GQ865518), 08-5-WH (FJ432717), and 11/09 (GU45715).