Zafar M Ammar, Wang Yang, Hamaguchi Shigeto, Weiser Jeffrey N
Department of Microbiology, New York University, New York, NY 10016, USA.
School of Medicine, Tsinghua University, 100084 Beijing, China; Department of Microbiology, New York University, New York, NY 10016, USA.
Cell Host Microbe. 2017 Jan 11;21(1):73-83. doi: 10.1016/j.chom.2016.12.005.
Host-to-host transmission is a critical step for infection. Here we studied transmission of the opportunistic pathogen Streptococcus pneumoniae in an infant mouse model. Transmission from nasally colonized pups required high levels of bacterial shedding in nasal secretions and was temporally correlated with, and dependent upon, the acute inflammatory response. Pneumolysin, a pore-forming cytotoxin and major virulence determinant, was both necessary and sufficient to promote inflammation, which increased shedding and allowed for intralitter transmission. Direct contact between pups was not required for transmission indicating the importance of an environmental reservoir. An additional in vivo effect of pneumolysin was to enhance bacterial survival outside of the host. Our findings provide experimental evidence of a microbial strategy for transit to new hosts and explain why an organism expresses a toxin that damages the host upon which it depends.
宿主间传播是感染的关键步骤。在此，我们在幼鼠模型中研究了机会致病菌肺炎链球菌的传播。来自鼻腔定植幼鼠的传播需要鼻腔分泌物中高水平的细菌脱落，并且在时间上与急性炎症反应相关且依赖于急性炎症反应。肺炎溶血素是一种形成孔道的细胞毒素和主要毒力决定因素，对于促进炎症反应既必要又充分，炎症反应增加了细菌脱落并允许在同窝幼鼠间传播。幼鼠之间的直接接触对于传播并非必需，这表明环境储存库的重要性。肺炎溶血素的另一个体内效应是增强细菌在宿主外的存活能力。我们的研究结果为微生物向新宿主传播的策略提供了实验证据，并解释了为何一种生物体表达一种会损害其赖以生存的宿主的毒素。
