Dengue is the widest spread vector-borne viral disease around the world and is transmitted mainly by the urban mosquito, Aedes aegypti. At present, vector control is the most widely used strategy to decrease disease incidence. However, it has demonstrated limited success. A new control strategy, associated with the manipulation of vector competence (VC) using endosymbiotic microorganisms, may be more sustainable because these microorganisms can influence mosquito development, the vector immune response, and vectorial capacity for infection with dengue virus (DENV). Hence, we explored the diversity of culturable midgut microbiota from two field-derived Aedes aegypti strains that are either susceptible or refractory to DENV infection and evaluated how strain-level dissection of the gut microbiome modulates VC. Microbial identification was carried out by mass spectrometry using MALDI-TOF, Vitek-2, BD Phoenix, and 16 s rRNA sequencing. There were differences in the composition and density of midgut microbiota in both mosquito strains. The refractory strain showed the highest microbial diversity and density with the highest prevalence of Gram-negative bacteria including Pseudomonas, Serratia, Stenotrophomonas, and Escherichia genera. In the susceptible strain, only Gram-positive bacteria of the Bacillus genus and Candida yeast were observed in the midgut. To evaluate the effect of midgut microbiota on DENV-2 infectivity in both Aedes aegypti strains, mosquitoes were treated with sugar and an antibiotic/antimycotic cocktail or sugar alone (the control) and were subsequently challenged with a mixture of blood and DENV-2. DENV-2 infection in the mosquitos’ heads (salivary glands) and midguts was evaluated after an extrinsic period of fourteen days with indirect immunofluorescence. A significant increase in DENV-2 susceptibility was observed in the treated refractory strain from 51.22% to 86.64% (Chi-square = 9.747, p < 0.05), while no changes were observed in the susceptible strain. These results confirm that susceptible and refractory mosquito strains may influence or are influenced by the presence of different gut microorganisms that affect virus infection susceptibility.

中文翻译：

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埃及伊蚊菌株中肠中可培养的微生物成分，对登革2型病毒的感染敏感性不同

登革热是全世界传播最广泛的媒介传播病毒病，主要通过城市蚊子埃及伊蚊传播。目前，病媒控制是减少疾病发生率最广泛使用的策略。但是，它显示出有限的成功。与使用共生共生微生物控制载体能力（VC）有关的新控制策略可能更具可持续性，因为这些微生物会影响蚊子的发育，载体免疫反应以及感染登革热病毒（DENV）的载体能力。因此，我们探索了两个田鼠埃及伊蚊的可培养中肠菌群的多样性。对DENV感染敏感或难治的菌株，并评估了肠道微生物组的菌株水平解剖如何调节VC。使用MALDI-TOF，Vitek-2，BD Phoenix和16 s rRNA测序，通过质谱进行微生物鉴定。两种蚊子中肠微生物群的组成和密度均存在差异。难治性菌株表现出最高的微生物多样性和密度，革兰氏阴性菌（包括假单胞菌，沙雷氏菌，嗜单胞菌和埃希氏菌属）的患病率最高。在易感菌株中，只有芽孢杆菌属和念珠菌的革兰氏阳性细菌在中肠观察到酵母。为了评估埃及伊蚊菌株中肠微生物群对DENV-2感染性的影响，蚊子分别用糖和抗生素/抗真菌混合物或糖（对照）处理，然后用血液和DENV-2的混合物攻击。在间接免疫荧光作用下，经过14天的外在感染后，评估了蚊子头部（唾液腺）和中肠的DENV-2感染情况。在治疗的难治性菌株中观察到DENV-2敏感性显着增加，从51.22％增至86.64％（卡方= 9.747，p <0.05），而在敏感菌株中未观察到变化。这些结果证实，易感和难治性蚊子菌株可能会影响不同肠道微生物的存在或受到影响，这些肠道微生物会影响病毒感染的易感性。