Epidemiological Survey Of Bovine Viral Diarrhea-mucosal Disease In Xinjiang

Bovine viral diarrhea-mucosaldisease(BVD/MD),which is caused by the RNA virus named by bovine viral diarrhea virus(BVDV)and characterized by a series of clinical symptoms such as diarrhea,fever,leukopenia,oral mucosal ulceration and pregnant female abortion and so on,is a bovine viral and contact infectious disease.The Ministry of Agriculture has announced that BVDV has been classified into three types of diseases,and the World Organisation for Animal Health(OIE)has also set it as Class B infectious disease.Obiective: Due to the increasing frequency of international cooperation and exchange trade and the high frequency mutation of RNA viruses,many new genotypes and gene subtypes have appeared in BVDB,which has caused certain difficulties in the prevention and control of BVDV.This study was conducted to diagnose and analyze suspected bovine viral diarrhea from a cattle farm in Xinjiang,and to do an epidemiological investigation,serological testing and molecular epidemiological testing in different breeds of cattle from different regions of Xinjiang in order to learn about the serological and molecular epidemiology of BVDV infection in different regions of Xinjiang,as well as the identification of genotypes and gene subtypes of epidemic strains.Methods: 1.Using the methods such as inquiries,clinical observations,16 cattle farms in 12 different regions of Xinjiang were investigated for the incidence of BVD/MD,the health of the herd,and the immunization and prevalence of the vaccine in cattle farms in different regions of Xinjiang.2.Applying on-site anatomy,sampling and inspection methods to diagnose the diarrhea of cattle in a cattle farm in Xinjiang.3.Using indirect ELISA antibody and antigen detection kit to detect BVDV antibody and antigen in 5833 serum samples collected from different regions of Xinjiang;4.The samples collected from the cattle suspected BVDV-positive cattle and serum antigens with high detection rate in northern Xinjiang were significantly isolated,cultured and identified in virus.And the same time,the cultured virus was inoculated into MDBK cells to observe the morphological structure of the cells,and then the cultured virus solution and the spleen tissues collected from the slaughterhouse were subjected to RNA extraction and RT.-PCR amplification,agarose gel electrophoresis analysis,positive result recovery and sequencing,analysis of correct sequences,construction of phylogenetic tree and other methods to analyze the main epidemic genotypes and gene subtypes of BVDV in Xinjiang.Results: 1.Different regions in Xinjiang have different BVDV infections due to differences in feeding management,breeding environment and vaccine immunity,among which north of Xinjiang is the highest,west and south is followed,and the east is the lowest.2.The cattle farm where diarrhea occurred was diagnosed as BVDV infection.3.Serological detection antibody positive rate was 52.03%(3035/5833),antigen positive rate was 3.35%(13/388),and the positive rate of yak and young cattle was higher than that of adult cattle.4.The main popular strain named JD001 in Xinjiang was successfully isolated from thecollected samples.No abnormality was observed in the cell morphology.14 of the RT-PCR results of 20 tissue samples were positive.Conclusion: 1.The infection of BVDV is different due to various aspects such as region and feeding management;2.Vaccination significantly increases the positive rate of antibody detection;3.The positive rate of antibody and antigen is different due to different farming modes,which means that the culture method does not affect the epidemic of the disease.In addition,the positive rate of the antigen calf and the pregnant cow is the highest,which indicates that the yak and the pregnant cow are susceptible to BVDV.4.The successful isolation of the main epidemic in northern Xinjiang.The strain JD001 was a non-cell-mutant strain,and the evolutionary analysis showed that the main genotype of Xinjiang was BVDV-1,and the gene subtype was 1q.The research on BVDV and epidemiological investigations at home and abroad suggest that the infection rate and harm of BVDV are quite serious,which has a huge burden on the economy.This research provides a theory for the prevention and control of BVDV in Xinjiang.