Zhang Xinyang, Crippen Tawni L, Coates Craig J, Wood Thomas K, Tomberlin Jeffery K
Department of Entomology, Texas A&M University, College Station, Texas, 77843, United States of America.
Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, United Kingdom.
PLoS One. 2015 Dec 16;10(12):e0143950. doi: 10.1371/journal.pone.0143950. eCollection 2015.
Aedes aegypti, the principal vector of yellow fever and dengue fever, is responsible for more than 30,000 deaths annually. Compounds such as carbon dioxide, amino acids, fatty acids and other volatile organic compounds (VOCs) have been widely studied for their role in attracting Ae. aegypti to hosts. Many VOCs from humans are produced by associated skin microbiota. Staphyloccocus epidermidis, although not the most abundant bacteria according to surveys of relative 16S ribosomal RNA abundance, commonly occurs on human skin. Bacteria demonstrate population level decision-making through quorum sensing. Many quorum sensing molecules, such as indole, volatilize and become part of the host odor plum. To date, no one has directly demonstrated the link between quorum sensing (i.e., decision-making) by bacteria associated with a host as a factor regulating arthropod vector attraction. This study examined this specific question with regards to S. epidermidis and Ae. aegypti. Pairwise tests were conducted to examine the response of female Ae. aegypti to combinations of tryptic soy broth (TSB) and S. epidermidis wildtype and agr- strains. The agr gene expresses an accessory gene regulator for quorum sensing; therefore, removing this gene inhibits quorum sensing of the bacteria. Differential attractiveness of mosquitoes to the wildtype and agr- strains was observed. Both wildtype and the agr- strain of S. epidermidis with TSB were marginally more attractive to Ae. aegypti than the TSB alone. Most interestingly, the blood-feeder treated with wildtype S. epidermidis/TSB attracted 74% of Ae. aegypti compared to the agr- strain of S. epidermidis/TSB (P ≤ 0.0001). This study is the first to suggest a role for interkingdom communication between host symbiotic bacteria and mosquitoes. This may have implications for mosquito decision-making with regards to host detection, location and acceptance. We speculate that mosquitoes "eavesdrop" on the chemical discussions occurring between host-associated microbes to determine suitability for blood feeding. We believe these data suggest that manipulating quorum sensing by bacteria could serve as a novel approach for reducing mosquito attraction to hosts, or possibly enhancing the trapping of adults at favored oviposition sites.
埃及伊蚊是黄热病和登革热的主要传播媒介，每年导致超过3万例死亡。二氧化碳、氨基酸、脂肪酸和其他挥发性有机化合物（VOCs）等化合物在吸引埃及伊蚊叮咬宿主方面的作用已得到广泛研究。许多来自人类的挥发性有机化合物是由相关的皮肤微生物群产生的。表皮葡萄球菌虽然根据16S核糖体RNA相对丰度的调查并非最丰富的细菌，但在人类皮肤上普遍存在。细菌通过群体感应表现出群体水平的决策。许多群体感应分子，如吲哚，会挥发并成为宿主气味羽流的一部分。迄今为止，还没有人直接证明与宿主相关的细菌的群体感应（即决策）作为调节节肢动物媒介吸引力的一个因素之间的联系。本研究针对表皮葡萄球菌和埃及伊蚊研究了这个具体问题。进行了成对测试以检查雌性埃及伊蚊对胰蛋白胨大豆肉汤（TSB）与表皮葡萄球菌野生型和agr-菌株组合的反应。agr基因表达一种用于群体感应的辅助基因调节器；因此，去除该基因会抑制细菌的群体感应。观察到蚊子对野生型和agr-菌株的吸引力存在差异。表皮葡萄球菌野生型和agr-菌株与TSB组合对埃及伊蚊的吸引力略高于单独的TSB。最有趣的是，用表皮葡萄球菌野生型/TSB处理的吸血者吸引了74%的埃及伊蚊，而表皮葡萄球菌agr-菌株/TSB吸引的埃及伊蚊为（P≤0.0001）。本研究首次表明宿主共生细菌与蚊子之间的跨界通讯具有作用。这可能对蚊子在宿主检测、定位和接受方面的决策产生影响。我们推测蚊子“偷听”宿主相关微生物之间发生的化学对话以确定是否适合吸血。我们相信这些数据表明，通过细菌操纵群体感应可以作为一种新方法来减少蚊子对宿主的吸引力，或者可能增强在有利产卵地点捕获成虫的能力。
