Reassessing the role of Internalin B in Listeria monocytogenes virulence using the epidemic strain F2365

Juan Quereda (1, 2) , Irene Rodríguez-Gómez (3) , Jazmín Meza-Torres (1) , Jaime Gomez-Laguna (3) , Marie Nahori (1) , Olivier Dussurget (4, 5, 1) , Librado Carrasco (3) , Pascale Cossart (1) , Javier Pizarro-Cerdá (1, 5, 6)

1 UIBC - Interactions Bactéries-Cellules
2 CEU-UCH - Universidad Cardenal Herrera-CEU
3 Universidad de Córdoba = University of Córdoba [Córdoba]
4 UPD7 - Université Paris Diderot - Paris 7
5 Yersinia
6 CNR - Centre National de Référence de la Peste et autres Yersinioses - National Reference Center Plague and Yersinioses

OBJECTIVES: We investigated the contribution to virulence of the surface protein Internalin B (InlB) in the L. monocytogenes lineage I strain F2365, which caused in California in 1985 one of the deadliest listeriosis outbreaks. METHODS: The F2365 strain displays a point mutation that hampers expression of InlB. We rescued the expression of InlB in the L. monocytogenes lineage I strain F2365 introducing a point mutation in the codon 34 (TAA to CAA) and investigated its importance for bacterial virulence using in vitro cell infection systems and a murine intravenous infection model. RESULTS: We show in HeLa and JEG-3 cells that the F2365 InlB+ strain expressing InlB was ≈9-fold and ≈1.5-fold more invasive than F2365, respectively. In livers and spleens of infected mice at 72 h post-infection bacterial counts for F2365 InlB+ were significantly higher compared to the F2365 strain (≈1 log more) and histopathological assessment showed that the F2365 strain displayed a reduced number of necrotic foci compared to the F2365 InlB+ strain (Mann-Whitney test). CONCLUSIONS: We describe a critical role for InlB during infection of non-pregnant animals by a L. monocytogenes strain from lineage I. Our study suggests that a spontaneous mutation in InlB could have prevented more severe human morbidity and mortality during the 1985 California listeriosis outbreak.

Mots clés: Epidemic; Infection; Internalin B; Invasion; Listeria monocytogenes

Domaines: Biologie moléculaire

Juan Quereda, Irene Rodríguez-Gómez, Jazmín Meza-Torres, Jaime Gomez-Laguna, Marie Nahori, et al.. Reassessing the role of Internalin B in Listeria monocytogenes virulence using the epidemic strain F2365. Clinical Microbiology and Infection, In press, ⟨10.1016/j.cmi.2018.08.022⟩. ⟨pasteur-01890600v1⟩