| As an acute and hot property infectious disease caused by bovine viral diarrhea-mucosal diseasevirus (BVDV), bovine viral diarrhea-Mucosal disease (BVD) is characterized by diarrhea, mucosaexfoliative, pregnant cow abortion, dead fetus and abnormal fetus, persistent infection andimmunotolerance, immunosupression. The epidemiological studies showed that BVD was widely prevalentin many countries and regions with developed cattle industry. The disease has been prevalent in more than20provinces with a high infection rates. Northern Xinjiang, as an important the livestock industryproducing areas in Xinjiang, there are some factors easily leading to the spread, such as a large number ofintroduction, a great many of cattle and sheep and trade frequently. In order to prevent and control of BVDin northern Xinjiang, it is necessary to carry out molecular epidemiology investigation, through which thegenotypes and genetic variation of BVDV epidemic strains could be understood.In this study, samples suspected BVDV infection were collected from northern Xinjiang to detectBVDV nucleic acid. Then, BVDV was isolated and identified from positive samples, then cloned andgenetic variation analysis of epidemic strain E2gene. The research methods and results were as follows:1. Molecular epidemiological survey of BVDV in Xinjiang northern. To understand the molecularbackground of BVDV epidemic strains in Xinjiang northern region, specific primers weredesigned,according to gene sequences of BVDV5’UTR which was published in GenBank, BVDV nucleicacid was detected from collected116samples. Parts of the selected positive samples were cloned andsequenced, then analyzing genotype for BVDV epidemic strains. The results showed that positive sampleswas66, infection rate of BVDV was56.90%, which indicated that BVDV infection was severe in northernXinjiang. In12randomly sequenced samples,11belonged to BVDV-1and1to BVDV-2. The resultsconfirmed that BVDV-1was the dominant genotype of epidemic strains, but BVDV-2infection alsoexisted in northern Xinjiang.2. Isolation and identification of BVDV-2epidemic strains in Xinjiang. The processed BVDV-2positive samples were inoculated on MDBK cells monolayers for virus isolation. One BVDV strain wassuccessfully isolated which can produce obvious cytopathic effect (CPE), The main characteristics of CPEwere that pathological cells gradually turned round, exfoliated, gathered into piles, netted, abscission anddied. We further confirmed the isolated strain belonged to genotype2by E2gene amplification, sequencingand sequence comparison.3. Cloning and genetic variation analysis of E2gene of BVDV epidemic strains in Xinjiang. Full-lengthof E2gene was amplified by nested PCR, and the amplified sequence were compared with the other E2genes from different regions. The results showed that the E2gene contained1120nucleotides. Sequenceanalysis found that identities of E2gene nucleotide sequence of BVDV-SW is more than86%compared with changchun184and Manasi, MNS2, the identities of amino acid sequences were high, reaching84%.Compared with the strains of C24V and NADL, the identities in the nucleotide and amino acid level are nomore than80%. The identities of BVDV2-SW with XJ-04and890were87%and84.7%, respectively;identities in amino acid are80.8%and79.9%. Phylogenetic analysis showed that BVDV-SW andBVDV2-SW strains belonged to BVDV-1and BVDV-2, respectively. Advantage epitope regions ofBVDV-SW were consistent with shihezi148, while BVDV2-SW was consistent with890and XJ-04.Genetic variation of E2genes was exists in BVDV-SW and BVDV2-SW epidemic strain. |
