Univ Lyon, INSA-Lyon, INRA, BF2I, UMR0203, F-69621, Villeurbanne, France.
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA.
BMC Microbiol. 2018 Nov 23;18(Suppl 1):150. doi: 10.1186/s12866-018-1278-5.
The tsetse fly (Glossina genus) is the main vector of African trypanosomes, which are protozoan parasites that cause human and animal African trypanosomiases in Sub-Saharan Africa. In the frame of the IAEA/FAO program 'Enhancing Vector Refractoriness to Trypanosome Infection', in addition to the tsetse, the cereal weevil Sitophilus has been introduced as a comparative system with regards to immune interactions with endosymbionts. The cereal weevil is an agricultural pest that destroys a significant proportion of cereal stocks worldwide. Tsetse flies are associated with three symbiotic bacteria, the multifunctional obligate Wigglesworthia glossinidia, the facultative commensal Sodalis glossinidius and the parasitic Wolbachia. Cereal weevils house an obligatory nutritional symbiosis with the bacterium Sodalis pierantonius, and occasionally Wolbachia. Studying insect host-symbiont interactions is highly relevant both for understanding the evolution of symbiosis and for envisioning novel pest control strategies. In both insects, the long co-evolution between host and endosymbiont has led to a stringent integration of the host-bacteria partnership. These associations were facilitated by the development of specialized host traits, including symbiont-housing cells called bacteriocytes and specific immune features that enable both tolerance and control of the bacteria. In this review, we compare the tsetse and weevil model systems and compile the latest research findings regarding their biological and ecological similarities, how the immune system controls endosymbiont load and location, and how host-symbiont interactions impact developmental features including cuticle synthesis and immune system maturation. We focus mainly on the interactions between the obligate symbionts and their host's immune systems, a central theme in both model systems. Finally, we highlight how parallel studies on cereal weevils and tsetse flies led to mutual discoveries and stimulated research on each model, creating a pivotal example of scientific improvement through comparison between relatively distant models.
采采蝇（舌蝇属）是非洲锥虫的主要传播媒介，非洲锥虫是一种原生动物寄生虫，会在撒哈拉以南非洲地区引起人类和动物的非洲锥虫病。在国际原子能机构/粮农组织“增强锥虫感染的媒介抗感染力”计划框架内，除了采采蝇之外，麦象鼻虫也被引入作为与内共生体免疫相互作用的比较系统。麦象鼻虫是一种农业害虫，会破坏全球很大一部分谷物库存。采采蝇与三种共生细菌有关，多功能专性共生菌 Wigglesworthia glossinidia、兼性共生菌 Sodalis glossinidius 和寄生性沃尔巴克氏体。麦象鼻虫与细菌 Sodalis pierantonius 建立了强制性营养共生关系，偶尔也与沃尔巴克氏体共生。研究昆虫宿主-共生体相互作用对于理解共生的进化和设想新的害虫控制策略非常重要。在这两种昆虫中，宿主和内共生体之间的长期共同进化导致了宿主-细菌伙伴关系的严格整合。这些关联得益于宿主特征的专门化发展，包括称为菌细胞的共生体容纳细胞和特定的免疫特征，这些特征既能使宿主容忍共生体又能控制共生体。在这篇综述中，我们比较了采采蝇和麦象鼻虫模型系统，并编译了关于它们的生物学和生态学相似性、免疫系统如何控制内共生体负荷和位置以及宿主-共生体相互作用如何影响包括表皮合成和免疫系统成熟在内的发育特征的最新研究结果。我们主要关注专性共生体与其宿主免疫系统之间的相互作用，这是两个模型系统的核心主题。最后，我们强调了对麦象鼻虫和采采蝇的平行研究如何导致相互发现，并刺激了对每个模型的研究，通过比较相对遥远的模型为科学进步创造了一个关键范例。
