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

Juan J. Quereda, Irene M. Rodríguez-Gómez, Jazmin Meza-Torres, Jaime Gómez-Laguna, Marie A. Nahori, Olivier Dussurget, Librado Carrasco, Pascale Cossart, Javier Pizarro-Cerdá
2018 Clinical Microbiology and Infection  
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. 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
more » ... e using in vitro cell infection systems and a murine intravenous infection model. 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). 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.
doi:10.1016/j.cmi.2018.08.022 pmid:30195066 pmcid:PMC6365677 fatcat:3wen2knyongzrit2ljmdya5nty