Investigation On Related Virus Of Calves’ Respiratory Disease In Large-scale Dairy Farms Of Some Areas In Xinjiang

Infectious bovine rhinotracheitis virus(IBRV), bovine parainfluenza virus type 3(BPIV3) and bovine respiratory syncytial virus(BRSV) are the main pathogen of bovine viral respiratory disease,them can cause great influence to dairy cows’ milk production、bulls’ fertility and fattening cattles’ weight gaining,and can decrease the immune function of cattle, easy to cause cows severe bronchitis and pneumonia when the cows secondly infecting bacterials or mycoplasma infection,causing serious economic losses to the cattle raising industry. In order to investigate the infections of the 3 virus in some areas of Xinjiang, we had collected 226 calf nasal discharge samples at less than one-month-old from main dairy in Shihezi,Sawan,Kuitun,Akesu and Kuerle,among them there were 180 sick calves’ nasal discharge samples and 40 nasal discharge samples of healthy calves at same age,by using double-antibody sandwich ELISA, PCR and RT-PCR to detect the infection of these three viruses,and analysising the virus’ nucleotide sequence and genotyping. The results are as follows:1. The infection rate of antigen sandwich ELISA method for detecting IBRV was 17.96%, the infection rates from different regions were 10.20% to 29.17%;and the infection rate of PCR method for detecting IBRV was 55.83%,the infection rates of five dairy farms in Kuitun,Shihezi,Shawan,Korla,Aksu areas wree respectively 44.90%, 46.67%,48.33%, 66.67% and 72.22%;it showed that the IBRV infection was widespread in the detected areas of Xinjiang. And tested virus strains evolved from a common ancestor with the reference strains of the United States and Brazil.2. The infection rate of antigen sandwich ELISA method for detecting BPIV3 was 2.34%,;and the infection rate of RT-PCR method for detecting BPIV3 was 35.44%, the infection rates of five dairy farms in Kuitun,Shihezi,Shawan,Korla,Aksu areas wree respectively 24.49%、28.00%、31.67%、44.44% and 45.83%; it showed that the BPIV3 infection was widespread in the detected areas of Xinjiang. Picking 8 detected BPIV3 virus analysising and comparing g M gene sequence, the homology was 97.90%,having a 93.0%-95.7% homology with the reference BPIV3 a subtype,and them evolved from a common ancestor with the reference strains of Australia BP13 JCU and the United States Kansas.we divided it into BPIV3 a subtype.3.PCR method to detect IBRV,the average infection rates of sick calves and healthy calves wree respectively 56.67% and 28.26%; RT-PCR method to detect BPIV3, the average infection rates of sick calves and healthy calves wree respectively 36.11% and 13.04%. It showed that both viruses play a role in bovine respiratory disease in detected dairy farms of part areas in Xinjiang,and the negative infections are present of IBRV and BPIV3.4. In the detected part areas of Xinjiang, there was a mixed infection of IBRV and BPIV3, the overall mixed infection rate was 9.73%.5. BRSV positive samples had not detected by using antigen sandwich ELISA method and RT-PCR method.It suggested there were no BRSV in detected samples from the main dairy farms of part areas in Xinjiang.The investigation had preliminarily investigating the infection of IBRV, BPIV3 and BRSV in part areas of Xinjiang,providing a preliminary theoretical basis for the prevention and control and vaccine development of the three viruses in Xinjiang areas.