Abstract:

Brucella，Chlamydia psittaci and Coxiella burnetii are three important zoonotic pathogens known to infect dairy cows.The aim of this study was to develop a multiplex PCR method for the simultaneous detection of them.Three genus-specific genes sequences were selected according to the GenBank，including Bp26 of Brucella spp., 23S rRNA of Chlamydia psittaci and IS1111a of Coxiella burnetii spp.And three specific primers pairs were designed respectively.After optimizing PCR reactions and amplification conditions，the multiplex method successfully discriminated Brucella，Chlamydia psittaci and Coxiella burnetii of dairy cows.The method had better specificity and repeatability，the detection sensitivity of simplex method for the three genes both reached 3.1×10² copies·reaction^－1，the detection sensitivity of multiplex method for these reached 3.1×10³ copies·reaction^－1.Using this multiplex method to detect 172 samples including bloods，serums，placentas and milk of different abortion cattle，53 Brucella positive samples，2 Chlamydia psittaci and 9 Coxiella burnetii positive samples were detected out，2 co-infection of Brucella and Chlamydia psittaci and 2 co-infection of Brucella and Coxiella burnetii positive samples were detected out else，no co-infection positive samples of the three pathogens was detected out.The above results indicated this method can be used for simultaneously，rapidly and sensitively detecting Brucella，Chlamydia psittaci and Coxiella burnetii of dairy cows.