Epidemiological Survey Of Bovine Viral Diarrhea In Henan Provinceand Local Isolates Identification

Abstract:Bovine viral diarrhea, BVD, caused by Bovine viral diarrhea virus, BVDV, is a complex disease with various clinical types. It is an infectious disease mainly invading pigs and ruminant animals, such as:cattle, sheep and yak. Its main clinical symptoms include respiratory syndrome, congenital defects, immune suppression, reproductive failure, colitis, immune tolerance’ and persistent infection, acute or chronic mucosal disease, dams miscarriage, stillbirth and fetal malformations and so on. The disease is inapparent infection and its main features are persistent infection and immune tolerance, as the Persistence and detoxification of the virus make it a constant source of infection. Bovine viral diarrhea distributes worldwide and are widely popular in many cattle industry developed countries of North and South America, Europe, Africa, Asia and Oceania.This test mainly proceed by RT-PCR for molecular epidemiology and ELISA for serological epidemiology investigation on BVDV infection in Henan Province. The total numbes of serum, milk, fecal was432,181,1069respectively from11dairy and6beef farms in9districts. The BVDV-positive rate of serum, milk, fecal was31.8%（124/395）,58.6%（106/181） respectively by ELISA method. BVDV-positive infecion rate of cattle fecal samples and serum samples was17.21%（184/1069） and59.46%（22/37） respectively. The results indicated that, there, was a serious BVDV infection in cattle in Zhengzhou, Zhumiadian, Jiyuan, Minquan, Lingbao of Henan Province. No clinical symptoms were observed in this investigation.Using Cell culture and RT-PCR technology, two isolates namely, BVDV-MQ01, BVDV MQ02were obtained and identified initially. CPE were fonud48h after the isolates were cultured in MDBK cell line, the monolayer cell began showed network structure, cells dead and shed off in DMEM..Through the phylogenetic analysis based on5’-UTR loci RT-PCR and sequencing, MEGA5analysis, Neighbor-Joining treeing, The results proved that the two isolates belong to BVDV gene type Ⅰ. MQO1has a relatively close evolutionary relationships with BJ10₁0and HUN0803, while, MQ02has a relatively close evolutionary relationships with TJO6and IS26NCP/01. From comparison of the analysis of nucleotide homology, MQ01and BJ10₁0have the highest homology of98.8%, hence they are the closest relatives. MQ02and TJ06have the highest homology of97.5%, therefore, they are the closest relatives.