Caetano-da-Silva Andrea, Ferre Ignacio, Collantes-Fernández Esther, Navarro Vanesa, Aduriz Gorka, Ugarte-Garagalza Carlos, Ortega-Mora Luis Miguel
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
Theriogenology. 2004 Oct 1;62(7):1329-36. doi: 10.1016/j.theriogenology.2004.01.010.
Recently, the presence of Neospora caninum DNA in semen from naturally infected bulls was reported. In the present work, the presence and quantification of N. caninum by PCR techniques in frozen extended semen straws from naturally infected bulls was investigated. A total of 20 seropositive and five seronegative bulls raised for reproductive purposes in an AI centre were used. Ten extended semen straws from each bull obtained at different time-points during the previous 2 years were selected for Neospora testing. Eight of the seropositive bulls (40%) studied showed at least one positive straw to N. caninum DNA and 14 of their 180 semen straws examined (7.8%) were found to be positive. In all positive samples, N. caninum DNA was consistently detected in the cell fraction and not in the seminal plasma. However, the parasite number in each positive straw was under the detection level of real-time PCR. In parallel, 10 semen straws from each of the five seronegative bulls were also analyzed by the nested-PCR and no N. caninum DNA products were obtained. In order to check the consistent presence of N. caninum in a positive semen batch, three additional semen straws from the same batch of each positive straw from three seropositive bulls were analyzed but N. caninum DNA was only detected in one straw from one bull. In conclusion, we report the sporadic detection of N. caninum DNA in semen straws of naturally infected bulls but the low frequency of contaminated semen straws and the low parasite load observed indicate a minor chance of bovine neosporosis transmission by AI.
最近，有报道称在自然感染牛的精液中存在犬新孢子虫DNA。在本研究中，采用聚合酶链式反应（PCR）技术对自然感染牛的冷冻稀释精液细管中犬新孢子虫的存在情况及定量进行了调查。总共使用了在一个人工授精中心饲养用于繁殖目的的20头血清学阳性公牛和5头血清学阴性公牛。从每头公牛在过去两年不同时间点获取的10根稀释精液细管中选取用于新孢子虫检测。所研究的8头血清学阳性公牛（40%）至少有一根精液细管对犬新孢子虫DNA呈阳性反应，在其检测的180根精液细管中有14根（7.8%）呈阳性。在所有阳性样本中，始终在细胞部分检测到犬新孢子虫DNA，而在精浆中未检测到。然而，每根阳性细管中的寄生虫数量低于实时PCR的检测水平。同时，对5头血清学阴性公牛每头的10根精液细管也进行了巢式PCR分析，未获得犬新孢子虫DNA产物。为了检查阳性精液批次中犬新孢子虫的持续存在情况，对来自3头血清学阳性公牛每根阳性细管同一批次的另外3根精液细管进行了分析，但仅在1头公牛的1根细管中检测到犬新孢子虫DNA。总之，我们报道了在自然感染公牛的精液细管中偶尔检测到犬新孢子虫DNA，但受污染精液细管的低频率以及观察到的低寄生虫载量表明通过人工授精传播牛新孢子虫病的可能性较小。
