Xenosurveillance: A Novel Mosquito-Based Approach for Examining the Human-Pathogen Landscape

BackgroundGlobally, regions at the highest risk for emerging infectious diseases are often the ones with the fewest resources. As a result, implementing sustainable infectious disease surveillance systems in these regions is challenging. The cost of these programs and difficulties associated with collecting, storing and transporting relevant samples have hindered them in the regions where they are most needed. Therefore, we tested the sensitivity and feasibility of a novel surveillance technique called xenosurveillance. This approach utilizes the host feeding preferences and behaviors of Anopheles gambiae, which are highly anthropophilic and rest indoors after feeding, to sample viruses in human beings. We hypothesized that mosquito bloodmeals could be used to detect vertebrate viral pathogens within realistic field collection timeframes and clinically relevant concentrations.Methodology/Principal FindingsTo validate this approach, we examined variables influencing virus detection such as the duration between mosquito blood feeding and mosquito processing, the pathogen nucleic acid stability in the mosquito gut and the pathogen load present in the host’s blood at the time of bloodmeal ingestion using our laboratory model. Our findings revealed that viral nucleic acids, at clinically relevant concentrations, could be detected from engorged mosquitoes for up to 24 hours post feeding by qRT-PCR. Subsequently, we tested this approach in the field by examining blood from engorged mosquitoes from two field sites in Liberia. Using next-generation sequencing and PCR we were able to detect the genetic signatures of multiple viral pathogens including Epstein-Barr virus and canine distemper virus.Conclusions/SignificanceTogether, these data demonstrate the feasibility of xenosurveillance and in doing so validated a simple and non-invasive surveillance tool that could be used to complement current biosurveillance efforts.全球范围内，新发传染病风险最高的地区往往也是资源最匮乏的区域。在此类地区搭建可持续的传染病监测系统极具挑战，相关项目的高额成本，以及样本采集、储存与运输环节的重重阻碍，都使得监测工作难以在最亟需的地区推进。为此，我们针对一种名为异源监测（xenosurveillance）的新型监测技术的敏感性与可行性开展了实证测试。该技术借助冈比亚按蚊（Anopheles gambiae）的宿主取食偏好与行为特征——这类按蚊具有极强的嗜人习性，且取食后会在室内停留——来采集人类体内的病毒样本。我们提出假说：在合理的野外样本采集时限内，且病毒浓度处于临床相关水平时，可通过蚊虫的血餐检测脊椎动物病毒性病原体。 方法与主要结果 为验证该方法的有效性，我们利用实验室模型，对影响病毒检测的多项关键变量进行了评估，包括蚊虫取血至标本处理的间隔时长、病原体核酸在蚊虫肠道内的稳定性，以及取食时宿主血液中的病原体载量。研究结果表明，在临床相关浓度下，通过实时荧光定量逆转录聚合酶链反应（qRT-PCR），可在吸饱血的蚊虫体内检出病毒核酸，最长检出时限可达取食后24小时。随后，我们在利比里亚的两处野外站点采集吸饱血的蚊虫血液，对该方法开展了实地验证。借助下一代测序（next-generation sequencing）与聚合酶链反应（PCR）技术，我们成功检测到多种病毒性病原体的遗传特征，包括EB病毒（Epstein-Barr virus）与犬瘟热病毒（canine distemper virus）。 结论与意义 综上，本研究数据证实了异源监测（xenosurveillance）的技术可行性，同时验证了一款简便无创的监测工具，可用于补充当前的生物监测工作体系。