Braquart-Varnier Christine, Altinli Mine, Pigeault Romain, Chevalier Frédéric D, Grève Pierre, Bouchon Didier, Sicard Mathieu
Laboratoire Écologie et Biologie des Interactions - Equipe Écologie, Évolution, Symbiose - UMR CNRS 7267, Université de Poitiers Poitiers, France.
Institut des Sciences de l'Évolution, CNRS-Université de Montpellier-IRD (UMR 5554) Montpellier, France.
Front Microbiol. 2015 Dec 16;6:1388. doi: 10.3389/fmicb.2015.01388. eCollection 2015.
Wolbachia is a vertically transmitted endosymbiont whose radiative success is mainly related to various host reproductive manipulations that led to consider this symbiont as a conflictual reproductive parasite. However, lately, some Wolbachia have been shown to act as beneficial symbionts by protecting hosts against a broad range of parasites. Still, this protection has been mostly demonstrated in artificial Wolbachia-host associations between partners that did not co-evolved together. Here, we tested in two terrestrial isopod species Armadillidium vulgare and Porcellio dilatatus whether resident Wolbachia (native or non-native) could confer protection during infections with Listeria ivanovii and Salmonella typhimurium and also during a transinfection with a Wolbachia strain that kills the recipient host (i.e., wVulC in P. dilatatus). Survival analyses showed that (i) A. vulgare lines hosting their native Wolbachia (wVulC) always exhibited higher survival than asymbiotic ones when infected with pathogenic bacteria (ii) P. dilatatus lines hosting their native wDil Wolbachia strain survived the S. typhimurium infection better, while lines hosting non-native wCon Wolbachia strain survived the L. ivanovii and also the transinfection with wVulC from A. vulgare better. By studying L. ivanovii and S. typhimurium loads in the hemolymph of the different host-Wolbachia systems, we showed that (i) the difference in survival between lines after L. ivanovii infections were not linked to the difference between their pathogenic bacterial loads, and (ii) the difference in survival after S. typhimurium infections corresponds to lower loads of pathogenic bacteria. Overall, our results demonstrate a beneficial effect of Wolbachia on survival of terrestrial isopods when infected with pathogenic intracellular bacteria. This protective effect may rely on different mechanisms depending on the resident symbiont and the invasive bacteria interacting together within the hosts.
沃尔巴克氏体是一种垂直传播的内共生菌，其广泛传播主要与各种宿主生殖操纵有关，这使得这种共生菌被视为一种具有冲突性的生殖寄生虫。然而，最近有研究表明，一些沃尔巴克氏体可作为有益共生菌，保护宿主抵御多种寄生虫。不过，这种保护作用大多是在未共同进化的伙伴之间的人工沃尔巴克氏体 - 宿主关联中得到证实的。在此，我们在两种陆生等足类动物普通卷甲虫（Armadillidium vulgare）和粗角卷甲虫（Porcellio dilatatus）中进行了测试，以探究常驻的沃尔巴克氏体（本地或非本地的）在感染伊凡诺夫李斯特菌（Listeria ivanovii）和鼠伤寒沙门氏菌（Salmonella typhimurium）期间，以及在接受一种能杀死受体宿主的沃尔巴克氏体菌株（即粗角卷甲虫中的wVulC）进行转染时，是否能提供保护。生存分析表明：（i）携带本地沃尔巴克氏体（wVulC）的普通卷甲虫品系在感染病原菌时，其存活率总是高于无共生菌的品系；（ii）携带本地wDil沃尔巴克氏体菌株的粗角卷甲虫品系在鼠伤寒沙门氏菌感染中存活得更好，而携带非本地wCon沃尔巴克氏体菌株的品系在感染伊凡诺夫李斯特菌以及接受来自普通卷甲虫的wVulC转染时存活得更好。通过研究不同宿主 - 沃尔巴克氏体系统血淋巴中伊凡诺夫李斯特菌和鼠伤寒沙门氏菌的载量，我们发现：（i）伊凡诺夫李斯特菌感染后品系间存活率的差异与它们病原菌载量的差异无关；（ii）鼠伤寒沙门氏菌感染后存活率的差异对应着病原菌载量的降低。总体而言，我们的结果证明了沃尔巴克氏体在陆生等足类动物感染致病性胞内细菌时对其生存具有有益作用。这种保护作用可能依赖于不同的机制，具体取决于宿主内共同作用的常驻共生菌和入侵细菌。
