Exposure to pairs of Aeromonas strains enhances virulence in the Caenorhabditis elegans infection model.
Exposure to pairs of Aeromonas strains enhances virulence in the Caenorhabditis elegans infection model.
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DOI：
10.3389/fmicb.2015.01218
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发表时间：
2015
影响因子：
5.2
通讯作者：
Lamy B
中科院分区：
文献类型：
--
作者：
Mosser T;Talagrand-Reboul E;Colston SM;Graf J;Figueras MJ;Jumas-Bilak E;Lamy B
气单胞菌的毒力仍然知之甚少，并且很难根据菌株特征进行预测。此外，感染通常是多种微生物感染（即混合感染），5-10% 的此类感染包括两种不同的气单胞菌，其对毒力的影响尚不清楚。在这项工作中，我们研究了从人类混合感染中恢复的气单胞菌的毒力。我们对它们进行了单独测试以及与其他菌株的联合测试，目的是提高我们对气单胞菌病的了解。从六种混合感染中成对回收的十二株菌株在秀丽隐杆线虫毒力模型中进行了测试。单独施用时，九种分离株对蠕虫杀伤力较弱（中位死亡时间，TD50，≥7 天）。与单一菌株感染相比，共感染后 TD50 显着缩短，表明两对病毒显示出更强的毒力。另外 14 个实验对中的 5 个也观察到毒力增强，并且每一对都包含来自天然协同对的一个菌株。这些实验表明协同效应很常见，并且仅限于由属于不同物种的菌株组成的对。毒力相关基因的基因组含量未能解释毒力协同作用，尽管某些菌株中存在的一些毒力相关基因在其伴生菌株（例如 T3SS）中不存在。当两种气单胞菌分离株共同感染时观察到的毒力协同作用强调了这样一个观点，即感染不仅仅取决于单一菌株的毒力，而是所涉及的微生物、宿主和环境之间更复杂的相互作用的结果。这些结果对于可能发生混合感染的其他疾病很有意义，特别是对于水传播疾病（例如军团菌病、弧菌病），其中病原体在合适的伙伴存在下可能表现出增强的毒力。这项研究有助于当前感染学范式的转变，从假设感染的单一微生物起源的前提转变为更符合当前病原体时代的假设。
Aeromonad virulence remains poorly understood, and is difficult to predict from strain characteristics. In addition, infections are often polymicrobial (i.e., are mixed infections), and 5–10% of such infections include two distinct aeromonads, which has an unknown impact on virulence. In this work, we studied the virulence of aeromonads recovered from human mixed infections. We tested them individually and in association with other strains with the aim of improving our understanding of aeromonosis. Twelve strains that were recovered in pairs from six mixed infections were tested in a virulence model of the worm Caenorhabditis elegans. Nine isolates were weak worm killers (median time to death, TD50, ≥7 days) when administered alone. Two pairs showed enhanced virulence, as indicated by a significantly shortened TD50 after co-infection vs. infection with a single strain. Enhanced virulence was also observed for five of the 14 additional experimental pairs, and each of these pairs included one strain from a natural synergistic pair. These experiments indicated that synergistic effects were frequent and were limited to pairs that were composed of strains belonging to different species. The genome content of virulence-associated genes failed to explain virulence synergy, although some virulence-associated genes that were present in some strains were absent from their companion strain (e.g., T3SS). The synergy observed in virulence when two Aeromonas isolates were co-infected stresses the idea that consideration should be given to the fact that infection does not depend only on single strain virulence but is instead the result of a more complex interaction between the microbes involved, the host and the environment. These results are of interest for other diseases in which mixed infections are likely and in particular for water-borne diseases (e.g., legionellosis, vibriosis), in which pathogens may display enhanced virulence in the presence of the right partner. This study contributes to the current shift in infectiology paradigms from a premise that assumes a monomicrobial origin for infection to one more in line with the current pathobiome era.