Hindgut microbiota in laboratory-reared and wild Triatoma infestans

Triatomine vectors transmit Trypanosoma cruzi, the etiological agent of Chagas disease in humans. Transmission to humans typically occurs when contaminated triatomine feces come in contact with the bite site or mucosal membranes. In the Southern Cone of South America, where the highest burden of disease exists, Triatoma infestans is the principal vector for T. cruzi. Recent studies of other vector-borne illnesses have shown that arthropod microbiota influences the ability of infectious agents to colonize the insect vector and transmit to the human host. This has garnered attention as a potential control strategy against T. cruzi, as vector control is the main tool of Chagas disease prevention. Here we characterized the microbiota in T. infestans feces of both wild-caught and laboratory-reared insects and examined the relationship between microbial composition and T. cruzi infection using highly sensitive high-throughput sequencing technology to sequence the V3-V4 region of the 16S ribosomal RNA gene on the MiSeq Illumina platform. We collected 59 wild (9 with T. cruzi infection) and 10 lab-reared T. infestans (4 with T. cruzi infection) from the endemic area of Arequipa, Perú. Wild T. infestans had greater hindgut bacterial diversity than laboratory-reared bugs. Microbiota of lab insects comprised a subset of those identified in their wild counterparts, with 96 of the total 124 genera also observed in laboratory-reared insects. Among wild insects, variation in bacterial composition was observed, but time and location of collection and development stage did not explain this variation. T. cruzi infection in lab insects did not affect α- or β-diversity; however, we did find that the β-diversity of wild insects differed if they were infected with T. cruzi and identified 10 specific taxa that had significantly different relative abundances in infected vs. uninfected wild T. infestans (Bosea, Mesorhizobium, Dietzia, and Cupriavidus were underrepresented in infected bugs; Sporosarcina, an unclassified genus of Porphyromonadaceae, Nestenrenkonia, Alkalibacterium, Peptoniphilus, Marinilactibacillus were overrepresented in infected bugs). Our findings suggest that T. cruzi infection is associated with the microbiota of T. infestans and that inferring the microbiota of wild T. infestans may not be possible through sampling of T. infestans reared in the insectary.锥蝽媒介（Triatomine vectors）可传播克氏锥虫（Trypanosoma cruzi）——人类恰加斯病（Chagas disease）的病原体。人类感染通常发生于污染的锥蝽粪便接触叮咬部位或黏膜时。在疾病负担最重的南美南部地区，骚扰锥蝽（Triatoma infestans）是克氏锥虫的主要传播媒介。此前针对其他虫媒传染病的研究已证实，节肢动物微生物群（arthropod microbiota）会影响病原体定殖昆虫媒介并传播至人类宿主的能力。这一发现引发了针对克氏锥虫潜在防控策略的关注，因为媒介防控是当前恰加斯病预防的主要手段。本研究中，我们从秘鲁阿雷基帕的流行区共收集了59只野外捕获的骚扰锥蝽（其中9只携带克氏锥虫）以及10只实验室饲养的骚扰锥蝽（其中4只携带克氏锥虫）。通过Illumina MiSeq测序平台对16S核糖体RNA基因的V3-V4可变区进行高灵敏度高通量测序，我们对野外捕获与实验室饲养的骚扰锥蝽粪便中的微生物群进行了表征，并探究了微生物群落组成与克氏锥虫感染状态之间的关联。分析显示，野外捕获的骚扰锥蝽后肠细菌多样性显著高于实验室饲养个体。实验室饲养锥蝽的微生物群仅为野外个体的子集，在总共检出的124个细菌属中，有96个同样在实验室饲养的锥蝽中被发现。在野外捕获的锥蝽中，细菌群落组成存在变异，但采集时间、地点以及昆虫发育阶段均无法解释这种变异。实验室饲养的锥蝽中，克氏锥虫感染并未对其α多样性或β多样性造成显著影响；然而本研究发现，携带克氏锥虫的野外锥蝽其β多样性与未感染个体存在显著差异，并鉴定出10个相对丰度存在显著差异的特异性类群：其中Bosea、Mesorhizobium、Dietzia及Cupriavidus在感染个体中丰度显著偏低；而Sporosarcina、未分类的Porphyromonadaceae菌属、Nestenrenkonia、Alkalibacterium、Peptoniphilus及Marinilactibacillus在感染个体中丰度显著偏高。本研究结果表明，克氏锥虫感染与骚扰锥蝽的微生物群存在显著关联，且无法通过实验室饲养的锥蝽样本推断野外骚扰锥蝽的微生物群落组成。