Detection and dissemination of Toxoplasma gondii in experimentally infected calves, a single test does not tell the whole story
Detection and dissemination of Toxoplasma gondii in experimentally infected calves, a single test does not tell the whole story
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DOI：
10.1186/s13071-018-2632-z
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发表时间：
2018-01-18
影响因子：
3.2
通讯作者：
Katzer, Frank
中科院分区：
文献类型：
--
作者：
Burrells, Alison;Taroda, Alessandra;Katzer, Frank
背景：虽然在牛组织中检测到刚地弓形虫是罕见的，但牛肉可能是人类感染的重要来源。磁性捕获qPCR （MC-qPCR）等分子技术与分离弓形虫的金标准方法（小鼠生物测定法）相结合，可提高感染牛中弓形虫检测的灵敏度。未煮熟/生牛肉将寄生虫传播给人类的风险尚不完全清楚，需要进一步了解牛体内弓形虫的偏好部位。在本研究中，6头荷斯坦奶牛（Bos taurus）实验感染了106个M4株弓形虫卵囊，并在安乐死（42 dpi）后，通过小鼠生物测定和MC-qPCR检测了池组织中弓形虫的存在。结果：采用MC-qPCR和小鼠生物测定方法，分别从肝脏、舌头、心脏、膈肌、半腱肌（后肢）、背最长肌（里脊）和腰肌大肌（里脊）的不同组织池（100 g）中检测到弓形虫。当选择用于小鼠生物测定的个体组织进行MC-qPCR检测时，尽管所有小牛在感染后都表现出血清转化，但只能从两只动物身上检测到寄生虫DNA。结论：很明显，一个单独的测试将不能提供一个答案，是否小牛窝藏弓形虫组织囊肿。虽然小牛接受了已知数量的感染性卵囊，并应用了高灵敏度的牛组织内寄生虫检测方法（小鼠生物测定法和MC-qPCR），但结果证实了先前的研究报告，即牛中有活力的弓形虫的存在率很低，而且牛组织内没有明确的偏爱部位。
Background: Although the detection of Toxoplasma gondii in bovine tissues is rare, beef might be an important source of human infection. The use of molecular techniques, such as magnetic capture qPCR (MC-qPCR), in combination with the gold standard method for isolating the parasite (mouse bioassay), may increase the sensitivity of T. gondii detection in infected cattle. The risk of transmission of the parasite to humans from undercooked/raw beef is not fully known and further knowledge about the predilection sites of T. gondii within cattle is needed. In the current study, six Holstein Friesian calves (Bos taurus) were experimentally infected with 106 T. gondii oocysts of the M4 strain and, following euthanasia (42 dpi), pooled tissues were tested for presence of the parasite by mouse bioassay and MC-qPCR.Results: Toxoplasma gondii was detected by both MC-qPCR and mouse bioassay from distinct pools (100 g) of tissues comprising: liver, tongue, heart, diaphragm, semitendinosus (hindlimb), longissimus dorsi muscle (sirloin) and psoas major muscle (fillet). When a selection of individual tissues which had been used for mouse bioassay were examined by MC-qPCR, parasite DNA could only be detected from two animals, despite all calves showing seroconversion after infection.Conclusions: It is apparent that one individual test will not provide an answer as to whether a calf harbours T. gondii tissue cysts. Although the calves received a known number of infectious oocysts and highly sensitive methods for the detection of the parasite within bovine tissues were applied (mouse bioassay and MC-qPCR), the results confirm previous studies which report low presence of viable T. gondii in cattle and no clear predilection site within bovine tissues.