Department of Biology, Baylor University, Waco, TX, USA.
Department of Biology, Jigjiga University, Jigjiga, Ethiopia.
Parasit Vectors. 2021 Dec 11;14(1):602. doi: 10.1186/s13071-021-05097-3.
The recent detection of the South Asian malaria vector Anopheles stephensi in the Horn of Africa (HOA) raises concerns about the impact of this mosquito on malaria transmission in the region. Analysis of An. stephensi genetic diversity and population structure can provide insight into the history of the mosquito in the HOA to improve predictions of future spread. We investigated the genetic diversity of An. stephensi in eastern Ethiopia, where detection suggests a range expansion into this region, in order to understand the history of this invasive population.
We sequenced the cytochrome oxidase subunit I (COI) and cytochrome B gene (CytB) in 187 An. stephensi collected from 10 sites in Ethiopia in 2018. Population genetic, phylogenetic, and minimum spanning network analyses were conducted for Ethiopian sequences. Molecular identification of blood meal sources was also performed using universal vertebrate CytB sequencing.
Six An. stephensi COI-CytB haplotypes were observed, with the highest number of haplotypes in the northeastern sites (Semera, Bati, and Gewana towns) relative to the southeastern sites (Kebridehar, Godey, and Degehabur) in eastern Ethiopia. We observed population differentiation, with the highest differentiation between the northeastern sites compared to central sites (Erer Gota, Dire Dawa, and Awash Sebat Kilo) and the southeastern sites. Phylogenetic and network analysis revealed that the HOA An. stephensi are more genetically similar to An. stephensi from southern Asia than from the Arabian Peninsula. Finally, molecular blood meal analysis revealed evidence of feeding on cows, goats, dogs, and humans, as well as evidence of multiple (mixed) blood meals.
We show that An. stephensi is genetically diverse in Ethiopia and with evidence of geographical structure. Variation in the level of diversity supports the hypothesis for a more recent introduction of An. stephensi into southeastern Ethiopia relative to the northeastern region. We also find evidence that supports the hypothesis that HOA An. stephensi populations originate from South Asia rather than the Arabian Peninsula. The evidence of both zoophagic and anthropophagic feeding support the need for additional investigation into the potential for livestock movement to play a role in vector spread in this region.
最近在非洲之角（HOA）发现了南亚疟疾传播媒介致倦库蚊，这引发了人们对该蚊子对该地区疟疾传播影响的担忧。分析致倦库蚊的遗传多样性和种群结构可以深入了解蚊子在 HOA 的历史，从而提高对未来传播范围的预测。我们调查了东埃塞俄比亚致倦库蚊的遗传多样性，因为在该地区的检测表明其分布范围有所扩大，以便了解这一入侵种群的历史。
我们在 2018 年从埃塞俄比亚的 10 个地点采集了 187 只致倦库蚊，对其进行了细胞色素氧化酶亚单位 I（COI）和细胞色素 B 基因（CytB）的测序。对埃塞俄比亚序列进行了种群遗传、系统发育和最小生成网络分析。还使用通用脊椎动物 CytB 测序对血液来源进行了分子鉴定。
观察到 6 种致倦库蚊 COI-CytB 单倍型，其中东北部（Semera、Bati 和 Gewana 镇）的单倍型数量最多，而东南部（Kebridehar、Godey 和 Degehabur）的单倍型数量较少。我们观察到种群分化，与东北部相比，东北部与中部（Erer Gota、Dire Dawa 和 Awash Sebat Kilo）和东南部的分化程度更高。系统发育和网络分析表明，HOA 的致倦库蚊与来自南亚的致倦库蚊比来自阿拉伯半岛的致倦库蚊在遗传上更为相似。最后，分子血液分析表明，它们的食物来源有牛、山羊、狗和人类，并且有混合血液摄入的证据。
我们表明，埃塞俄比亚的致倦库蚊在遗传上是多样的，并且具有地理结构的证据。多样性水平的变化支持了这样一种假设，即与东北部地区相比，致倦库蚊在埃塞俄比亚东南部的引入时间相对较近。我们还发现了支持 HOA 致倦库蚊种群起源于南亚而不是阿拉伯半岛的证据。关于动物和人类血液摄入的证据支持了这样一种假设，即家畜的迁移可能在该地区的传播中发挥作用，需要进一步调查。
