Kortebi Mounia, Milohanic Eliane, Mitchell Gabriel, Péchoux Christine, Prevost Marie-Christine, Cossart Pascale, Bierne Hélène
Micalis Institute, Inra, AgroParisTech, Université Paris-Saclay, Equipe Epigénétique et Microbiologie Cellulaire, Jouy-en-Josas, France.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America.
PLoS Pathog. 2017 Nov 30;13(11):e1006734. doi: 10.1371/journal.ppat.1006734. eCollection 2017 Nov.
Listeria monocytogenes causes listeriosis, a foodborne disease that poses serious risks to fetuses, newborns and immunocompromised adults. This intracellular bacterial pathogen proliferates in the host cytosol and exploits the host actin polymerization machinery to spread from cell-to-cell and disseminate in the host. Here, we report that during several days of infection in human hepatocytes or trophoblast cells, L. monocytogenes switches from this active motile lifestyle to a stage of persistence in vacuoles. Upon intercellular spread, bacteria gradually stopped producing the actin-nucleating protein ActA and became trapped in lysosome-like vacuoles termed Listeria-Containing Vacuoles (LisCVs). Subpopulations of bacteria resisted degradation in LisCVs and entered a slow/non-replicative state. During the subculture of host cells harboring LisCVs, bacteria showed a capacity to cycle between the vacuolar and the actin-based motility stages. When ActA was absent, such as in ΔactA mutants, vacuolar bacteria parasitized host cells in the so-called "viable but non-culturable" state (VBNC), preventing their detection by conventional colony counting methods. The exposure of infected cells to high doses of gentamicin did not trigger the formation of LisCVs, but selected for vacuolar and VBNC bacteria. Together, these results reveal the ability of L. monocytogenes to enter a persistent state in a subset of epithelial cells, which may favor the asymptomatic carriage of this pathogen, lengthen the incubation period of listeriosis, and promote bacterial survival during antibiotic therapy.
单核细胞增生李斯特菌可引起李斯特菌病，这是一种食源性疾病，会对胎儿、新生儿和免疫功能低下的成年人构成严重风险。这种细胞内细菌病原体在宿主细胞质中增殖，并利用宿主肌动蛋白聚合机制在细胞间传播并在宿主体内扩散。在此，我们报告，在感染人肝细胞或滋养层细胞的数天时间里，单核细胞增生李斯特菌从这种活跃的运动型生活方式转变为在液泡中持续存在的阶段。在细胞间传播后，细菌逐渐停止产生肌动蛋白成核蛋白ActA，并被困在称为含李斯特菌液泡（LisCVs）的溶酶体样液泡中。细菌亚群在LisCVs中抵抗降解并进入缓慢/非复制状态。在含有LisCVs的宿主细胞传代培养过程中，细菌显示出在液泡和基于肌动蛋白的运动阶段之间循环的能力。当ActA不存在时，例如在ΔactA突变体中，液泡中的细菌以所谓的“活的但不可培养”状态（VBNC）寄生在宿主细胞中，从而无法通过传统的菌落计数方法检测到它们。将感染细胞暴露于高剂量庆大霉素不会触发LisCVs的形成，但会选择液泡细菌和VBNC细菌。总之，这些结果揭示了单核细胞增生李斯特菌在上皮细胞亚群中进入持续状态的能力，这可能有利于该病原体的无症状携带，延长李斯特菌病的潜伏期，并促进抗生素治疗期间细菌的存活。
