Protein mass spectrometry extends temporal blood meal detection over polymerase chain reaction in mouse-fed Chagas disease vectors

BACKGROUND Chagas disease is highly prevalent in Latin America, and vector control is the most effective control strategy to date. We have previously shown that liquid chromatography tandem mass spectrometry (LC-MS/MS) is a valuable tool for identifying triatomine vector blood meals. OBJECTIVES The purpose of this study was to determine blood meal detection ability as a function of method [polymerase chain reaction (PCR) vs. LC-MS/MS], time since feeding, and the effect of molting in mouse-fed triatomine insect vectors targeting hemoglobin and albumin proteins with LC-MS/MS and short interspersed nuclear elements (SINE)-based PCR. METHODS We experimentally fed Triatoma protracta on mice and used LC-MS/MS to detect hemoglobin and albumin peptides over time post-feeding and post-molting (≤ 12 weeks). We compared LC-MS/MS results with those of a standard PCR method based on SINEs. FINDINGS Hemoglobin-based LC-MS/MS detected blood meals most robustly at all time points post-feeding. Post-molting, no blood meals were detected with PCR, whereas LC-MS/MS detected mouse hemoglobin and albumin up to 12 weeks. MAIN CONCLUSIONS In our study, the hemoglobin signature in the insect abdomen lasted longer than that of albumin and DNA. LC-MS/MS using hemoglobin shows promise for identifying triatomine blood meals over long temporal scales and even post-molting. Clarifying the frequency of blood-feeding on different hosts can foster our understanding of vector behavior and may help devise sounder disease-control strategies, including Ecohealth (community based ecosystem management) approaches.

背景：查加斯病（Chagas disease）在拉丁美洲流行率极高，媒介防控是迄今最为有效的防控策略。本团队此前的研究已证实，液相色谱串联质谱（liquid chromatography tandem mass spectrometry，LC-MS/MS）是鉴定锥蝽媒介血源的可靠工具。

目标：本研究旨在明确血源检测能力随检测方法[聚合酶链式反应（polymerase chain reaction，PCR）与LC-MS/MS]、采血后时长以及蜕皮事件的变化规律，并探究蜕皮对检测结果的影响，针对小鼠饲喂的锥蝽，分别采用LC-MS/MS靶向检测血红蛋白与白蛋白，以及基于短散在核元件（short interspersed nuclear elements，SINE）的PCR方法开展分析。

方法：我们通过实验让长足锥蝽（Triatoma protracta）吸食小鼠血液，在采血后及蜕皮后的不同时间节点（≤12周）利用LC-MS/MS检测血红蛋白与白蛋白肽段，并将LC-MS/MS的检测结果与基于SINE的标准PCR方法进行对比。

结果：基于血红蛋白的LC-MS/MS在所有采血后时间点均能稳定且高效地检出血源。蜕皮后，PCR未检出任何血源，而LC-MS/MS可在12周内检测到小鼠血红蛋白与白蛋白。

主要结论：本研究显示，昆虫腹部的血红蛋白信号留存时长长于白蛋白与DNA。基于血红蛋白的LC-MS/MS方法在长时程甚至蜕皮后的锥蝽血源鉴定中展现出良好应用前景。明确不同宿主的吸血频率，有助于深化对媒介昆虫行为的理解，或可助力制定更科学的疾病防控策略，包括生态健康（Ecohealth，基于社区的生态系统管理）方法。