摘要目的:建立实时荧光定量PCR方法检测布鲁氏菌基因组内IS711转座酶基因（orfA基因）的拷贝数，并应用于布鲁氏菌种与生物型的鉴定。方法:构建基于Taqman探针法实时荧光定量PCR技术的orfA基因拷贝数的检测体系。设计bcsp31基因和orfA基因的引物和探针，应用实时荧光定量PCR方法同时检测同一菌株相同DNA浓度下的bcsp31基因和orfA基因含量，获得2个基因的循环数（CT值），再根据bcsp31基因和orfA基因CT值的差异，换算出待检测布鲁氏菌菌株基因组内orfA基因的拷贝数。同时，将布鲁氏菌16M菌株DNA进行2倍递减稀释，验证检测体系的稳定性。结果:当16M菌株DNA浓度相差2倍时，实时荧光定量PCR方法同时检测bcsp31基因和orfA基因，测得的CT值差值均值均为1.00，95%置信区间为0.95~1.05，标准差为0.17，变异系数为0.17。应用该检测体系检测30株布鲁氏菌菌株DNA中orfA基因的拷贝数，发现羊种生物1~3型菌株分别有6、9和7个拷贝数；猪种生物2型菌株有10个拷贝数，与其他4个猪种生物型（1、3~5）菌株拷贝数不同；绵羊附睾种菌株有37个拷贝数；8个牛种生物型（1~7、9）菌株拷贝数稳定在5~6个。结论:成功建立了一种检测布鲁氏菌orfA基因拷贝数的实时荧光定量PCR方法，该方法能够鉴定部分布鲁氏菌种与生物型菌株。

abstractsObjective:To establish a real-time quantitative PCR assay to detect the copy number of IS711 transposase gene (orfA) in Brucella genome, and the assay is applied to identify the species and biovars of Brucella. Methods:To establish an orfA gene copy number detection system based on Taqman real-time quantitative PCR technique. Primers and probes of bcsp31 and orfA genes were designed, the contents of bcsp31 gene and orfA gene in the same strain with the same DNA concentration were simultaneously detected by real-time quantitative PCR assay, and cycle number (CT value) of the two genes were obtained. According to the differences of CT values of bcsp31 gene and orfA gene, the copy number of orfA gene in Brucella genome was calculated. At the same time, the DNA of Brucella 16M strain was double decreasing dilution to verify the stability of the detection system. Results:A real-time quantitative PCR assay was used to detect bcsp31 gene and orfA gene simultaneously, when the DNA concentration difference of 16M strain was 2 times, the mean difference of CT values measured was 1.00, 95% confidence interval was 0.95-1.05, standard deviation was 0.17, and coefficient of variation was 0.17. The orfA gene copy number of 30 Brucella strains was detected by this detection system. It was found that there were 6, 9, and 7 copy numbers in the biovars 1-3 of Brucella melitensis, respectively. The strain of Brucella suis biovar 2 had 10 copy numbers, which were different from those of the other 4 strains of biovars 1, 3-5. There were 37 copy numbers in Brucella ovis strain. The copy numbers were stable at 5-6 copies in 8 biovars (1-7, 9) of Brucella abortus strains. Conclusions:A real-time quantitative PCR assay for detection of orfA gene copy number in Brucella DNA has been established. This method could identify some Brucella species and biovars strains.