Isolation and biological characterization of mink enteritis virus in Shandong province

Abstract:

[Objective]This study aims to investigate the genomic characteristics of mink enteritis virus (MEV) in Shandong province, China. [Methods]A total of 109 fecal samples were collected from mink farms for the isolation and identification of MEV strains. Biological characterization of the isolates was carried out based on hemagglutination and hemagglutination inhibition tests, multistep growth curves, and protein structure prediction. The genomic DNA sequences of the isolates were amplified, cloned, and sequenced. MegAlign was employed for multiple sequence alignment and DNAMAN V6 for the prediction of the inverted terminal repeats of 5ʹ-untranslated region (UTR) and 3ʹ-UTR. The neighbor-joining phylogenetic tree was constructed in MEGA V6. [Results] Five strains were isolated and identified as MEV by electron microscopy and indirect immunofluorescence assay (IFA), which were named as MUTQS-1, MUTQS-2, MUTQS-3, MUTQS-4, and MUTQS-5, respectively. The genomic sequences were submitted to GenBank and got the accession numbers OK275645, OK275646, OK275647, OK275648, and OK275649, respectively. The 5ʹ- and 3ʹ-UTRs consisted of long palindromic sequences with a typical stem-loop-like structure at the end of parvovirus genome. The deduced amino acid sequences of NS1 and VP2 genes had several nonsynonymous mutations, among which E/Q545V in NS1 protein and F267Y and Y324I in VP2 protein had not been reported. Biological characterization showed that the above mutations did not significantly alter the hemagglutination and hemagglutination inhibition titers, growth trend, and spatial conformation of viral particles. The phylogenetic tree suggested that the five MEV isolates shared the same clade and were closely related to the Shandong isolate SDNH.[Conclusion] We reported the genomic characteristics of MEV strains containing novel mutation sites and confirmed that the presence of these sites did not alter the hemagglutination, antigenicity, or proliferation in susceptible cells.

Key words:mink enteritis virus;genetic variation;biological characteristics