Isolation And Identification Of A Strain Bovine Parainfluenza Virus Type 3 In Inner Mongolia

In this study,swabs were collected from a dairy farm in Inner Mongolia that was suspected to have been infected with bovine parainfluenia virus,and MDBK cells were inoculated after treatment for virus isolation and reproduction.The virus was identified by molecular biology,serology,physical and chemical characteristics of the virus,electron microscopy,genetic evolution system analysis,and the infectivity and immunogenicity of the virus in cattle.The results showed that the virus can proliferate on MDBK cells and produce stable lesions.Molecular biological identification showed that the electrophoresis bands of the RT-PCR amplification products of the isolated virus were the same size as the BPIV3 target gene fragments.Serological identification showed that the isolated virus could be neutralized by BPIV3 positive serum and had agglutination effect on guinea pig red blood cells,with the minimum agglutination titer not less than 1:16,this agglutination of red blood cells were inhibited by BPIV3 positive serum.The virus was very sensitive to ethyl and chloroform.After treatment at 37? for 60 minutes,the TCID50 of virus decreased significantly.After treatment at 56? for 60 minutes and 80? for 30 minutes,the virus was completely inactivated.When the pH value is lower than 5.0 or higher than 8.0,the TCID50 of virus decreases significantly.The results of electron microscopy showed that the virus was irregular,and the size was about 200nm.The whole genome of the isolated virus was sequenced,and the results of comparative analysis of gene evolution tree showed that the virus isolate belonged to genotype C,and belonged to the same subtype as SD0835.Infectious studies on cattle showed that the virus could cause disease in cattle,pathological sections showed different degrees of lesions in trachea,lungs and lymph nodes.The above identification results indicate that the virus isolate was a bovine parainfluenza type 3 virus.Further test results show that the BPIV3 strain isolate has good immunogenicity.