Establishment Of An Indirect ELISA For Detection Of Antibody Against Bovine Viral Diarrhea Virus And Its Clinical Serology Investigation

BVD is a disease caused by BVDV, also known as mucosal disease. Distribution of the virus is world-wide. Bovine infected by BVDV showed diarrhea, acute and chronic mucosal diaease, persistent infection and immunotolerance, immunosupression, pregnant cow abortion, dead fetus and abnormal fetus. Acute infections may result in transient diarrhoea or pneumonia, usually in the form of group outbreaks. Acute forms of the disease associated with high mortality have also been described, often, but not always, associated with a haemorrhagic syndrome. However, most infections in the young calf are mild and go unrecognised clinically. The virus spreads mainly by contact among cattle. Vertical transmission plays an important role in its epidemiology and pathogenesis. Calves infected with the virus are usually mild and do not compare the performance of clinical symptoms. Because of their reproductive system can cause the formation of lesions and persistent infection, so the cattle industry has an important impact.BVDV and classical swine fever virus (CSFV), sheep border disease virus (DBV) and some unclassified disease virus belong to flaviviridae. The virus is a single positive-strand RNA virus.This virus was considered the host specificity, but studies have shown that BVDV and DBV can infect with a wider range of hosts, they can infect not only cattle and sheep but multiple artiodactyl animals including pigs. BVD has less clinical symptoms characteristic and was difficult to diagnose, in addition to it's low case fatality rate, so it fails to attract enough attention to this disease. The lack of the systematic monitoring control measures is also the reason of causing BVDV infection in cattle growing in my country.Because the cow have been infection and its extremely harmful to the cattle industry, the cattle survey and therefore, detection of their infection is nessary.BVDV's non-structural protein NS3 protein is very conservative in the virus disease, and is a immunodominance protein. In the natural infection or live attenuated vaccines in animals after immunization can generate antibodies. Our laboratory selected a stronger immune response of the recombinant fragment (rBVDV-NS3b) as coating antigen to establish an indirect ELISA method. Compared with the import kit the rate of coincidence is 91.3%.To survey the prevalence of bovine viral diarrhea virus in Heilongjiang Province, We used a indirect ELISA, which detected the antibody to BVDV NS3,to examine 1388 serum samples from 2006 to 2008,which collected from four ranches. The results showed that the percentages of the serum samples having the antibody to BVDV were 54.66%,57.68% and 62.90% from 2006 to 2008. The results demonstrated that the infection rate of BVDV was in high level and increasing in Heilongjiang Province.