Sobyanin Konstantin, Sysolyatina Elena, Krivozubov Mikhail, Chalenko Yaroslava, Karyagina Anna, Ermolaeva Svetlana
Gamaleya Research Center of Epidemiology and Microbiology, Department of Infections with Natural Foci, Gamaleya St. 18, Moscow 123098, Russia.
Gamaleya Research Center of Epidemiology and Microbiology, Department of Bacterial Genetics and Molecular Biology, Gamaleya St. 18, Moscow 123098, Russia.
FEMS Microbiol Lett. 2017 Feb 1;364(3). doi: 10.1093/femsle/fnx011.
Listeria monocytogenes is a causative agent of foodborne infection in humans and animals. The virulence factor InlB interacts with mammalian receptor c-Met via its internalin domain to provide L. monocytogenes invasion in non-professional phagocytes. Naturally occurring InlB internalin domain variants form four subclusters on the maximal likelihood tree. Four variants belonging to distinct subclusters were cloned into the vector carrying 3΄ and 5΄-flanking sequences to restore full length inlB and expressed in the L. monocytogenes strain EGDeΔinlB. The substitutions Val132Ile, Thr117Ala and Ile138Leu, Thr251Met/Ser were specific for variants 13, 14 and 1, respectively, the variant 9 carried Ser73Asn, Ile91Val, Leu164Pro, Met251Ser/Thr substitutions. All InlB variants improved invasion of the parental strain in murine colon carcinoma C26 cells with 4.6-fold difference between the most and least effective variants (variants 14 and 13, respectively, P < 0.05). Bacterial loads in livers of intragastrically infected mice were 258, 149 and 92 times higher for variant 14, 13 and 1 carrying strains, respectively, than for EGDeΔinlB (P < 0.01). In contrast, the variant 9 did not noticeably improve infection comparatively to the parental strain. Overall, obtained results demonstrated that naturally occurred InlB internalin domain variants differed in their ability to support intragastric infection in mice.
单核细胞增生李斯特菌是人和动物食源性感染的病原体。毒力因子InlB通过其内化素结构域与哺乳动物受体c-Met相互作用，使单核细胞增生李斯特菌能够侵入非专职吞噬细胞。天然存在的InlB内化素结构域变体在最大似然树上形成四个亚群。将属于不同亚群的四个变体克隆到携带3΄和5΄侧翼序列的载体中，以恢复全长inlB，并在单核细胞增生李斯特菌菌株EGDeΔinlB中表达。Val132Ile、Thr117Ala和Ile138Leu、Thr251Met/Ser替换分别是变体13、14和1所特有的，变体9携带Ser73Asn、Ile91Val、Leu164Pro、Met251Ser/Thr替换。所有InlB变体均提高了亲代菌株对小鼠结肠癌C26细胞的侵袭能力，最有效和最无效的变体（分别为变体14和13）之间相差4.6倍（P < 0.05）。经胃内感染的小鼠肝脏中的细菌载量，携带变体14、13和1的菌株分别比EGDeΔinlB高258、149和92倍（P < 0.01）。相比之下，变体9与亲代菌株相比，并未显著改善感染情况。总体而言，所得结果表明，天然存在的InlB内化素结构域变体在支持小鼠胃内感染的能力方面存在差异。
