Bishop R P, Hemmink J D, Morrison W I, Weir W, Toye P G, Sitt T, Spooner P R, Musoke A J, Skilton R A, Odongo D O
International Livestock Research Institute (ILRI), PO Box 30709, Nairobi, 00100, Kenya.
The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG Scotland, UK.
Int J Parasitol Parasites Wildl. 2015 Aug 29;4(3):333-42. doi: 10.1016/j.ijppaw.2015.08.006. eCollection 2015 Dec.
African Cape buffalo (Syncerus caffer) is the wildlife reservoir of multiple species within the apicomplexan protozoan genus Theileria, including Theileria parva which causes East coast fever in cattle. A parasite, which has not yet been formally named, known as Theileria sp. (buffalo) has been recognized as a potentially distinct species based on rDNA sequence, since 1993. We demonstrate using reverse line blot (RLB) and sequencing of 18S rDNA genes, that in an area where buffalo and cattle co-graze and there is a heavy tick challenge, T. sp. (buffalo) can frequently be isolated in culture from cattle leukocytes. We also show that T. sp. (buffalo), which is genetically very closely related to T. parva, according to 18s rDNA sequence, has a conserved orthologue of the polymorphic immunodominant molecule (PIM) that forms the basis of the diagnostic ELISA used for T. parva serological detection. Closely related orthologues of several CD8 T cell target antigen genes are also shared with T. parva. By contrast, orthologues of the T. parva p104 and the p67 sporozoite surface antigens could not be amplified by PCR from T. sp. (buffalo), using conserved primers designed from the corresponding T. parva sequences. Collectively the data re-emphasise doubts regarding the value of rDNA sequence data alone for defining apicomplexan species in the absence of additional data. 'Deep 454 pyrosequencing' of DNA from two Theileria sporozoite stabilates prepared from Rhipicephalus appendiculatus ticks fed on buffalo failed to detect T. sp. (buffalo). This strongly suggests that R. appendiculatus may not be a vector for T. sp. (buffalo). Collectively, the data provides further evidence that T. sp. (buffalo). is a distinct species from T. parva.
非洲水牛（非洲水牛属）是顶复门原生动物泰勒虫属多种物种的野生动物宿主，其中包括导致牛东海岸热的小泰勒虫。自1993年以来，一种尚未正式命名的寄生虫，即泰勒虫（水牛种），基于核糖体DNA（rDNA）序列被认为可能是一个独特的物种。我们通过反向线杂交（RLB）和18S rDNA基因测序证明，在水牛和牛共同放牧且蜱虫大量侵袭的地区，泰勒虫（水牛种）可经常从牛白细胞培养物中分离出来。我们还表明，根据18S rDNA序列，与小泰勒虫在基因上密切相关的泰勒虫（水牛种），具有多态性免疫显性分子（PIM）的保守直系同源物，该分子是用于小泰勒虫血清学检测的诊断酶联免疫吸附测定（ELISA）的基础。几个CD8 T细胞靶抗原基因的密切相关直系同源物也与小泰勒虫共有。相比之下，使用根据相应小泰勒虫序列设计的保守引物，无法通过PCR从小泰勒虫（水牛种）中扩增出小泰勒虫p104和p67子孢子表面抗原的直系同源物。总体而言，这些数据再次强调了在缺乏其他数据的情况下，仅靠rDNA序列数据来定义顶复门物种的价值存在疑问。对从以水牛为食的微小牛蜱制备的两个泰勒虫子孢子稳定株的DNA进行“深度454焦磷酸测序”，未能检测到泰勒虫（水牛种）。这强烈表明微小牛蜱可能不是泰勒虫（水牛种）的传播媒介。总体而言，这些数据进一步证明泰勒虫（水牛种）是与小泰勒虫不同的物种。
