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

J J Quereda (1, 2) , I M Rodríguez-G Omez (3) , J Meza-Torres (1) , Jaime Gomez-Laguna (3) , Marie-Anne Nahori (1) , O Dussurget (4, 1, 5) , L 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: To investigate the contribution to virulence of the surface protein internalin B (InlB) in the Listeria monocytogenes lineage I strain F2365, which caused a deadly listeriosis outbreak in California in 1985. 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 by introducing a point mutation in the codon 34 (TAA to CAA). We investigated its importance for bacterial virulence using in vitro cell infection systems and a murine intravenous infection model. Results: In HeLa and JEG-3 cells, 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 hours after infection, bacterial counts for F2365 InlB+ were significantly higher compared to the F2365 strain (≈1 log more), and histopathologic assessment showed that the F2365 strain displayed a reduced number of necrotic foci compared to the F2365 InlB+ strain (Mann-Whitney test). Conclusions: InlB plays a critical role during infection of nonpregnant animals by a L. monocytogenes strain from lineage I. A spontaneous mutation in InlB could have prevented more severe human morbidity and mortality during the 1985 California listeriosis outbreak.

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

Domaines: Bactériologie

J J Quereda, I M Rodríguez-G Omez, J Meza-Torres, Jaime Gomez-Laguna, Marie-Anne Nahori, et al.. Reassessing the role of internalin B in Listeria monocytogenes virulence using the epidemic strain F2365. Clinical Microbiology and Infection, 2019, 25 (2), pp.252.E1-252.E4. ⟨10.1016/j.cmi.2018.08.022⟩. ⟨pasteur-01890600v2⟩