Bacterial abundance in larval flasks over time.

Aedes aegypti mosquitoes are a major vector of arboviruses that oviposit in both artificial containers (i.e., buckets, tires, cans) and natural containers (i.e., coconut husks, tree holes). These diverse container types will seed the larvae microbiome with differing bacterial communities. While the larval microbiome has been shown to alter adult susceptibility to arboviruses including dengue (DENV) and Zika virus (ZIKV), it is not known if exposure to different bacterial communities found between container types impacts adult Ae. aegypti interactions with arboviruses. To address this, rainwater was collected from an artificial container (plastic buckets) and a natural container (coconut husks) from three different collection sites and the microbiomes were preserved. Larval exposure to plastic bucket-derived microbiomes resulted in adults with increased susceptibility to ZIKV compared to larval exposure to coconut husk-derived microbiomes from all three collection sites, indicating that the container type, independent of collection environment, drives variation in adult susceptibility to ZIKV. 16S amplicon sequencing of larvae exposed to the preserved microbiomes revealed that bacterial community structure differed between plastic bucket and coconut husk derived communities at each collection site, but a conserved plastic- or coconut-derived bacterial community across collection sites was not identified. However, water from coconut husks had significantly more total bacterial abundance than water from plastic buckets. Normalization of bacterial loads between container types resulted in similar ZIKV infection rates. Together, these data suggest that larval exposure to specific container type-associated microbiomes alters adult susceptibility to ZIKV, largely driven by differences in total bacterial density between container types. Results from this study will help understand how the urbanization-driven expansion of Ae. aegypti into new/different oviposition sites might affect arbovirus susceptibility.

埃及伊蚊（Aedes aegypti）是虫媒病毒（arboviruses）的主要传播媒介，其产卵场所涵盖人工容器（如水桶、轮胎、易拉罐）与自然容器（如椰壳、树洞）。这类多样的容器类型会为幼虫微生物组（larval microbiome）引入不同的细菌群落。尽管已有研究证实，幼虫微生物组会改变成蚊对登革病毒（DENV）与寨卡病毒（ZIKV）等虫媒病毒的易感性，但目前尚不清楚暴露于不同容器类型间存在的差异细菌群落，是否会影响埃及伊蚊成蚊与虫媒病毒的相互作用。为解答这一科学问题，研究人员从3个不同采集点的人工容器（塑料水桶）与自然容器（椰壳）中收集雨水，并保存其中的微生物组。相较于暴露于3个采集点来源的椰壳微生物组的幼虫，暴露于塑料水桶来源微生物组的幼虫发育为成蚊后，对寨卡病毒的易感性显著升高，这表明容器类型独立于采集环境，可驱动成蚊对寨卡病毒易感性的差异。对暴露于保存微生物组的幼虫进行16S扩增子测序（16S amplicon sequencing）后发现，在每个采集点，塑料水桶与椰壳来源的细菌群落结构均存在显著差异，但未在不同采集点间发现保守的塑料或椰壳来源细菌群落。不过，椰壳来源雨水的总细菌丰度显著高于塑料水桶来源雨水。对两类容器来源的细菌载量进行标准化处理后，成蚊的寨卡病毒感染率趋于一致。综合以上结果，本研究数据表明，幼虫暴露于与特定容器类型相关的微生物组会改变成蚊对寨卡病毒的易感性，这一效应主要由两类容器间的总细菌密度差异所介导。本研究结果有助于理解城市化驱动下埃及伊蚊向新型/不同产卵场所扩张的现象，会如何影响其对虫媒病毒的易感性。