The Selection Of BVDV-PI Cattle And Isolation、Identification Of BVDV Strain On Large-scale Cattle Farms In Changji

Bovine viral diarrhea（BVD）which is caused by bovine viral diarrhea virus（BVDV）is a contagious infectious disease of cattle,and it clinical manifestations included diarrhea,abortion,persistently infected and immunosuppression.Because of the lack of effective vaccine,BDV has extensively existed in many parts of China,which has resulted in enormous economic loss.The aim of this study were that screened the BVDV-PI cattle and isolated the BVDV Xinjiang strain on large-scale cattle farms in Changji city.This article was composed by the following three parts:（1）Total 450 samples were detected by loop-mediated isothermal amplification（LAMP）to screen the BVDV cattle.The results showed that 22 samples were positive,and the positive rate was 4.89%.（2）The positive BVDV samples were rechecked by quantitative real-time RT-PCR（Q-PCR）,and BVDV-PI cattle were screened after three weeks.The results showed that 19samples were positive,and the positive rate was 83.36%;14 BVDV-PI cattle had been screened.（3）BVDV was isolated and identified from BVDV-PI cattle by cell culture experiment,RT-PCR and direct fluorescence immunoassay assay.The results showed that 14 BVDV strains were obtained.4 strains were CPE,the TCID₅₀ of these strains were4.65×10⁵¹.98×10⁷TCID₅₀/0.1mL;and 10 strains were NCPE,the TCID₅₀ were1.58×10⁴⁷.65×10⁸TCID₅₀/0.1mL.Included,This study could provide background information for understanding the epidemic situation of BVDV in Changji city,and BVDV XinJiang strains could provide material base for the preparation of BVDV vaccine.