Meta Analysis Of The Prevalence Of IBR In Dairy Cows In My Country And The Establishment Of Its GE-iELISA Method

Bovine herpesvirus 1(BHV-1),an important pathogen of cattle,can cause severe clinical syndromes including respiratory disease,genital disease,and late-term abortions,as well as neurological and systemic disease in cattle.Respiratory diseases in calves are responsible for major economic losses in both the beef and dairy production industries.Currently,there are reports of infections of IBRV around the world.In China,IBR is very popular among dairy cows,and the overall prevalence is not clear.At present,the detection of IBR in China mainly relies on imported kits.Its detection cost is high.It is necessary to establish a low-cost,fast,accurate,high-throughput detection method,and it is suitable for conducting surveys of IBR prevalence in dairy herds.Our study used a meta-analysis method for systematic evaluation and comprehensive analysis.We assessed the overall prevalence of IBR in China and the risk factors that influence its serological susceptibility.This report provides a theoretical basis for the development of prevention and control measures.At the same time,the IBRV gE recombinant protein was used as the coating protein to establish a gE-iELISA detection method suitable for the immune labeled vaccine.It is ideal for IBR monitoring,screening,epidemiological investigations,vaccine immunization and differential diagnosis of natural infections.We provide technical supports for the long-term development of the Chinese dairy industry.(1)As of December 31,2018,4357 articles related to the IBR epidemic in China are in the database.After screening and evaluation,we extracted the standardized data of 42 documents that met the requirements for meta-analysis.In different publications,the total prevalence of 45238 cows from 7 administrative districts was 40%(95%CI: 33-46),of which the prevalence of cows in the Northwest was 43%(95%CI: 32-54;2989/6243);There is a difference in the prevalence of dairy cows between provinces,with a seroprevalence rate of 12% to 66%;compared with the diagnostic methods of LAT,PCR,VNT,and IHA(17%,95%CI: 10-24;511/3160),The detection rate using ELISA was higher(45%,95%CI: 39-52;17887/42078).The prevalence rates of cow loss in different stages were 23%(95%CI:8-38;436/1268),33%(95%CI:21-45;881/2063)and 49%(95%CI:38-60;4463/9709),respectively.The prevalence of IBR from 2013 to 2018 was higher than before 2013,with 43%(95%CI: 35-50;15487/35675)and 34%(95%CI: 24-43;2911/9563).The results showed that the prevalence of IBR in dairy cows in China is rising and unevenly distributed.It is further confirmed that IBRV infection in Chinese dairy cattle herds has become more and more serious in recent years.The prevalence of IBR is related to the time of publication,test methods,study area,age,clinical symptoms(pneumonia,abortion,etc.).It reveals the prevalence of IBRV in dairy cows in mainland China.We must monitor the prevalence of IBR in dairy cows.In order to prevent the spread of the disease,we should take strong and effective regulatory measures.(2)We synthesized the IBRV gE gene by gene synthesis and optimized the codons.The pET32a-gE recombinant plasmid was constructed and then transformed into BL21 competent cells for induction expression.Induced effect in IPTG concentration tendency for 1.0mmol/L,induction time 4h,at 37? for the best.The size of the expressed gE recombinant protein was about 43 kDa by SDS-PAGE.The protein concentration was 0.159mg/mL using a nickel column purification.We verified by Western blot that gE recombinant protein can react with positive serum.It has excellent reactivity,which is consistent with the expected results.The results indicated that the gE recombinant protein has been successfully expressed.It lays the foundation for the establishment of diagnostic methods,vaccine development and mechanism research.(3)Using the purified gE protein as the coating,we optimized the reaction conditions and established an indirect ELISA for bovine infectious rhinotracheitis(IBR gE-iELISA)to determine the cut-off value.The gE-iELISA was used to detect bovine viral diarrhea positive serum,bovine epidemic fever positive serum,bovine parainfluenza positive serum and bovine adenovirus positive serum.The calculated S/P(%)values were all less than 37.9%.And there was no cross-reaction,with good specificity;The intra-assay coefficient of variation and the coefficient of variation between batches are less than 10%;Compared with the IDEXX kit,its compliance rate is 92.7%.The IBR gE-iELISA established in this study can be used for epidemiological investigation of IBR in dairy farms.