Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences (TUMS), Tehran, Iran.
Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran.
Parasit Vectors. 2019 Jan 7;12(1):10. doi: 10.1186/s13071-018-3273-y.
Leishmaniasis is caused by Leishmania parasites and is transmitted to humans through the bite of infected sand flies. Development of Leishmania to infective metacyclic promastigotes occurs within the sand fly gut where the gut microbiota influences development of the parasite. Paratransgenesis is a new control method in which symbiotic bacteria are isolated, transformed and reintroduced into the gut through their diet to express anti-parasitic molecules. In the present study, the midgut microbiota of three sand fly species from a steppe and a mountainous region of northern Iran, where zoonotic visceral leishmaniasis (ZVL) is endemic, was investigated.
Briefly, adult female sand flies was collected during summer 2015 and, after dissection, the bacterial composition of the guts were analyzed using a culture-dependent method. Bacterial DNA from purified colonies was extracted to amplify the 16S rRNA gene which was then sequenced.
Three ZVL sand fly vectors including Phlebotomus major, P. kandelakii and P. halepensis were found in the highlighted regions. In total, 39 distinct aerobic bacterial species were found in the sand fly midguts. The sand fly microbiota was dominated by Proteobacteria (56.4%) and Firmicutes (43.6%). Bacterial richness was significantly higher in the steppe region than in the mountainous region (32 vs 7 species). Phlebotomus kandelakii, the most important ZVL vector in the study area, had the highest bacterial richness among the three species. Bacillus subtilis and Pantoea agglomerans were isolated from the guts of the sand flies; these are already used for the paratransgenesis of sand flies and mosquitoes, respectively.
The existence of B. subtilis and P. agglomerans in the ZVL vectors and other sand fly species studied so far suggests that these two bacterial species are potential candidates for paratransgenic approach to prevent ZVL transmission. Further research needs to test the possible relationship between the gut microbiome richness and the vector competence of the ZVL vectors.
利什曼病是由利什曼原虫引起的，通过受感染的沙蝇叮咬传播给人类。利什曼原虫发育为感染性的循环前鞭毛体发生在沙蝇的肠道内，肠道微生物群影响寄生虫的发育。共生体转基因是一种新的控制方法，其中共生细菌被分离、转化，并通过饮食重新引入肠道，以表达抗寄生虫分子。本研究调查了伊朗北部草原和山区三种沙蝇物种的中肠微生物群，该地区是动物源性内脏利什曼病（ZVL）的流行区。
简要地说，在 2015 年夏季收集成年雌性沙蝇，解剖后，使用依赖培养的方法分析肠道的细菌组成。从纯化的菌落中提取细菌 DNA 以扩增 16S rRNA 基因，然后对其进行测序。
在所强调的地区发现了三种 ZVL 沙蝇传播媒介，包括 P. major、P. kandelakii 和 P. halepensis。在沙蝇中肠中总共发现了 39 种不同的需氧细菌。沙蝇微生物群主要由变形菌门（56.4%）和厚壁菌门（43.6%）组成。草原地区的细菌丰富度明显高于山区（32 种对 7 种）。在所研究的地区，P. kandelakii 是最重要的 ZVL 传播媒介，其物种丰富度在三种物种中最高。从沙蝇的肠道中分离出枯草芽孢杆菌和成团泛菌；这些细菌已经分别用于沙蝇和蚊子的共生体转基因。
在 ZVL 媒介和迄今为止研究的其他沙蝇物种中存在 B. subtilis 和 P. agglomerans 表明，这两种细菌是预防 ZVL 传播的共生体转基因方法的潜在候选者。需要进一步研究来测试肠道微生物组丰富度与 ZVL 媒介媒介能力之间的可能关系。
