Molecular characterization of Trypanosoma vivax in tsetse flies confirms the presence of the virulent Tvv4 genotype in Kenya: Potential implications for the control of trypanosomiasis in Shimba Hills
Molecular characterization of Trypanosoma vivax in tsetse flies confirms the presence of the virulent Tvv4 genotype in Kenya: Potential implications for the control of trypanosomiasis in Shimba Hills
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DOI：
10.1016/j.meegid.2021.104953
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发表时间：
2021-06-09
影响因子：
3.2
通讯作者：
Okal, Michael N.
中科院分区：
文献类型：
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作者：
Ebhodaghe, Faith I.;Bastos, Armanda D. S.;Okal, Michael N.
间日锥虫是一种媒介传播的原生动物寄生虫，在非洲和南美洲流行。迄今为止，在东非的脊椎动物和昆虫宿主中已经描述了15种寄生虫基因型。然而，关于T.间日疟的多样性在该次区域的许多流行国家仍然有限，包括肯尼亚。这些信息可以加深对辛巴山动物锥虫病当地流行病学的了解，辛巴山是肯尼亚东南部的一个野生动物区，T。间日疟原虫是地方病，感染牲畜。我们采用双基因常规PCR测序和系统发育分析对T. 2018年11月至2019年9月在辛巴山国家保护区的野生动物-牲畜界面收集的采采蝇中的间日疟基因型。利用ITS-1序列分析了中国南方红豆杉的系统发育。间日疟原虫分离株证实存在两个T. Shimba Hills的间日疟基因型中，>80%的T.来自采采蝇的间日疟原虫分离株聚集在毒性Tvv 4基因型进化枝内。Tvv 4基因型的采采蝇感染也基于18 S rRNA基因测序得到证实。扩展的基因表征确定了Tvv 4进化枝内的三个密切相关的单倍型。在雄性和雌性Glossina pallidipes采采蝇中检测到Tvv 4分离株，其中大部分是从草原和Shimba Hills国家保护区边界两公里内收集的。考虑到T。间日疟原虫是辛巴山地区最常见的锥虫，并导致牲畜严重的临床状况，肯尼亚首次报道的Tvv 4基因型有助于我们了解这些病理。目前尚不清楚杀锥虫药物在Tvv 4管理中的有效性。因此，新巴山区的寄生虫管理应以病媒生物控制为主，降低寄生虫密度。苍白足，尤其是在野生动物保护区附近的草原上。
Trypanosoma vivax is a vector-borne protozoan parasite of livestock endemic to Africa and South America. To date, fifteen genotypes of the parasite have been described in vertebrate and insect hosts in East Africa. However, information regarding T. vivax diversity remains limited in many endemic countries in the sub-region, including Kenya. Such information could deepen insight into the local epidemiology of animal trypanosomiasis in Shimba Hills, a wildlife area in southeast Kenya where T. vivax is endemic and infects livestock. We employed two-gene conventional-PCR-sequencing and phylogenetic analysis to characterize T. vivax genotypes in tsetse flies collected between November 2018 and September 2019 in the wildlife-livestock interface of the Shimba Hills National Reserve. Phylogenetic analysis of Internal Transcribed Spacer-1 (ITS-1) sequences of T. vivax isolates confirmed the presence of two T. vivax genotypes in Shimba Hills of which >80% of T. vivax isolates from tsetse flies clustered within the virulent Tvv4-genotype clade. Tsetse infections with the Tvv4 genotype were also confirmed based on 18S rRNA gene sequencing. Expanded gene characterization identified three closely related haplotypes within the Tvv4-clade. The Tvv4-isolates were detected in male and female Glossina pallidipes tsetse flies, most of which were collected from grasslands and within two kilometres of the Shimba Hills National Reserve boundary. Considering that T. vivax is the most common trypanosome in the Shimba Hills area and causes severe clinical conditions in livestock, the Tvv4 genotype reported here for the first time in Kenya contributes to our understanding of these pathologies. The effectiveness of trypanocidal drugs in the management of Tvv4 is presently not clearly understood. Therefore, the parasite management in Shimba Hills should focus on vector control to reduce the density of G. pallidipes, especially in grasslands near the wildlife protectorate.