Pienaar Ronel, Latif Abdalla A, Mans Ben J
Epidemiology, Parasites and Vectors, Agricultural Research Council-Onderstepoort Veterinary Research, Onderstepoort, 0110, South Africa.
School of Life Sciences, University of KwaZulu-Natal, Durban, Westville, South Africa.
Vet Parasitol. 2018 Apr 30;254:30-35. doi: 10.1016/j.vetpar.2018.03.003. Epub 2018 Mar 3.
All Theileria parasites have definitive natural hosts that act as carriers. Incidental infections of uncommon hosts do occur raising questions regarding host specificity and its drivers. Reported hosts for Theileria taurotragi include bushbuck, cattle and eland. More recently T. taurotragi was detected in African buffalo, which may have implications for accurate diagnostics of T. parva. The current study therefore investigated the host specificity of T. taurotragi by developing a specific and sensitive real-time Taqman PCR assay. Animals were screened from areas where Rhipicephalus appendiculatus, the tick vector for both T. parva and T. taurotragi was present. While T. taurotragi was detected in cattle, eland, kudu and nyala, African buffalo (n = 352) was negative. Conversely, these same buffalo showed a prevalence of 72-100% for T. parva. While transmission of T. taurotragi to cattle was successful using the same infected tick batch, transmission to African buffalo did not occur. The results suggest that African buffalo is not a natural host of T. taurotragi and would probably not harbor anti-schizont antibodies against T. taurotragi. This would preclude T. taurotragi as possible source of cross-reactivity in the T. parva immunofluorescent antibody test. Host specificity of T. taurotragi for members of the Tragelaphini, but not buffalo also suggests that host specificity may have been an important driver in the speciation of the T. taurotragi clade. Different scenarios for co-evolution of host and parasite are discussed with implications for time of divergence for this Theileria clade.
所有泰勒虫属寄生虫都有作为携带者的明确自然宿主。不常见宿主的偶然感染确实会发生，这引发了关于宿主特异性及其驱动因素的问题。报道的泰勒虫的宿主包括薮羚、牛和大羚羊。最近在非洲水牛中检测到了泰勒虫，这可能对小泰勒虫的准确诊断有影响。因此，本研究通过开发一种特异性和敏感性高的实时Taqman PCR检测方法，研究了泰勒虫的宿主特异性。从存在小泰勒虫和泰勒虫的蜱传播媒介——肩突硬蜱的地区筛选动物。虽然在牛、大羚羊、捻角羚和林羚中检测到了泰勒虫，但非洲水牛（n = 352）呈阴性。相反，这些相同的水牛显示小泰勒虫的感染率为72%-100%。虽然使用同一批感染蜱成功地将泰勒虫传播给了牛，但未发生传播给非洲水牛的情况。结果表明，非洲水牛不是泰勒虫的自然宿主，可能也不会携带针对泰勒虫的抗裂殖体抗体。这将排除泰勒虫作为小泰勒虫免疫荧光抗体检测中可能的交叉反应来源。泰勒虫对旋角羚亚科成员而非水牛的宿主特异性也表明，宿主特异性可能是泰勒虫进化枝物种形成的一个重要驱动因素。讨论了宿主与寄生虫共同进化的不同情况及其对该泰勒虫进化枝分化时间的影响。
