背景:肝细胞动物fitzsimonsi(Dias,1953年)是南部非洲乌龟的一种常见血液。在该物种从Haemogregarina属重新分配到Hepatozoon时,在与H.fitzsimonsi寄生和非寄生的乌龟相关的蜱中观察到了孢子囊和子孢子等发育阶段。因此,有人认为蜱可能是这种寄生虫的潜在载体。然而,这项较早的研究无法使用分子标记确认这些孢子形成阶段的身份。在另一项旨在鉴定寄生南非爬行动物的tick物种并对其进行分子筛查的研究中,该研究在与乌龟相关的蜱中发现了H.fitzsimonsi。因此,本研究旨在使用显微镜和分子方法相结合的方法,重新研究壁虱作为乌龟中H.fitzsimonsi的载体的潜力。
方法:纳他克尼克斯的标本,Kinixysspekii,从Bonamanzi和Ndumo野味保护区收集了Kinixyszombensis和Stigmochelyspardalis,南非。捕获后,检查动物的蜱,这些是与血液和其他组织一起收集的。解剖成年蜱,并在干净的显微镜载玻片上制备内脏印模载玻片以及稀薄的血液和组织涂片。涂片和印模载玻片用Giemsa染色,筛选并捕获寄生虫的显微照片。使用两个引物组来靶向在乌龟和壁虱中发现的寄生虫的18SrRNA基因的片段,然后将所得序列与GenBank数据库中其他已知的H.fitzsimonsi和hemogregarine序列进行比较。
结果:在延髓中观察到外周血gamont和肝脏merogonic分期,而在Amblyomma的ecoel中观察到了孢子形成阶段。Gamont和孢子囊期在形态上与以前对H.fitzsimonsi的描述进行了比较,将它们识别为这个物种。系统发育分析显示,在这项研究中获得的血液和tick序列聚集在包含已知H.fitzsimonsi的单系进化枝中。
结论:本研究通过分子鉴定和联系观察到的乌龟发育阶段,为壁虱充当H.fitzsimonsi的载体提供了进一步的支持(S.pardalis)与无脊椎动物寄主中的那些(Amblyommaspp。).
BACKGROUND: Hepatozoon fitzsimonsi (Dias, 1953) is a frequently found haemogregarine of southern African tortoises. At the time of this species\' reassignment from the genus Haemogregarina to Hepatozoon, developmental stages such as sporocysts and sporozoites were observed in ticks associated with H. fitzsimonsi parasitised and non-parasitised tortoises. It was thus suggested that ticks may act as the potential vectors for this parasite. However, this earlier research was unable to confirm the identity of these sporogonic stages using molecular markers. In a separate study aimed at identifying tick species parasitising South African reptiles and molecularly screening these for the presence of Hepatozoon, that study identified H. fitzsimonsi in tortoise-associated ticks. Thus, the present study aimed to revisit the potential of ticks to act as vectors for H. fitzsimonsi in tortoises using a combined microscopy and molecular approach.
METHODS: Specimens of Kinixys natalensis, Kinixys spekii, Kinixys zombensis and Stigmochelys pardalis were collected from Bonamanzi and Ndumo Game Reserve, South Africa. Upon capture, animals were examined for ticks, and these were collected along with blood and other tissues. Adult ticks were dissected and visceral impression slides were prepared along with thin blood and tissue smears on clean microscope slides. Smears and impression slides were stained with Giemsa, screened and micrographs of parasites were captured. Two primer sets were employed to target fragments of the 18S rRNA gene of parasites found in both tortoises and ticks and the resulting sequences were then compared with other known H. fitzsimonsi and haemogregarine sequences from the GenBank database.
RESULTS: Peripheral blood gamont and liver merogonic stages were observed in S. pardalis, while the sporogonic stages were observed in the haemocoel of Amblyomma ticks. Gamont and sporocyst stages compared morphologically with previous descriptions of H. fitzsimonsi, identifying them as this species. Phylogenetic analysis revealed that the blood and tick sequences obtained in this study clustered in a monophyletic clade comprising known H. fitzsimonsi.
CONCLUSIONS: The present study provides further support for ticks acting as the vectors of H. fitzsimonsi by molecularly identifying and linking observed developmental stages in tortoises (S. pardalis) with those in the invertebrate host (Amblyomma spp.).