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Spatio-temporal expression of the PagN Salmonella entry factor in the three commonly used murine models

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Abstract

Salmonella are among the top-ranked foodborne pathogens, inducing a wide variety of diseases ranging from gastroenteritis to typhoid fever, depending on the infecting serovar, the host and its genetic background. The virulence of this bacterium is mainly dependent on its ability to enter and multiply into host cells including non-phagocytic cells. As a facultative intracellular pathogen, it can induce its own internalization through at least 3 different bacterial factors: the Salmonella pathogenicity island 1 (SPI-1)-encoded type three secretion system-1 (T3SS-1), and two outer membrane proteins, Rck and PagN. The chromosomal pagN gene is part of the PhoP/PhoQ regulon, and was identified, through the use of in vivo expression technology, as a gene required for Salmonella Typhimurium survival in BALB/c mice. PagN is a widely conserved 27 kDa protein displaying both structure and function homology with the Hek and Tia adhesins and invasins of E. coli. This invasin allows Salmonella to invade eukaryotic cells through a Zipper-like mechanism, following interaction with heparan sulfate proteoglycans and 1 integrin. However, its precise role in vivo remains to be determined including the cells targeted by this invasin. In this study, we aimed to precisely determine the kinetics of expression of PagN in mice using the lux operon of Photorhabdus luminescens and bioluminescence imaging. S. Typhimurium reporter strains carrying luminescent transcriptional fusions in the attTn7 site on the chromosome were used to follow pagN transcription in murine models reproducing the three main pathologies induced by Salmonella, i.e. typhoid fever, gastroenteritis and asymptomatic carriage. We observed a transcription of pagN in the intestine independently of the genetic background of the host and the inflammatory state of the animals. However, differences in the kinetics were observed in this organ depending of the animal model. Moreover, pagN transcription was detected at later time points in lymphoid organs following the systemic spread of the pathogen in the typhoid fever and gastroenteritis reproducing models. These results demonstrate for the first time that pagN is expressed in the intestine and that its expression is different according to the pathology induced by Salmonella. Further analyses based on the kinetics observed in this study and focusing on the identification of the cells targeted by PagN in the different mouse models, are in progress using flow cytometry, fluorescence-activated cell sorting, confocal microscopy and immuno-histochemistry.
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Dates and versions

hal-03730930 , version 1 (20-07-2022)

Identifiers

  • HAL Id : hal-03730930 , version 1

Cite

Michael Koczerka, Olivier Grépinet, Isabelle Lantier, Marie Morillon, Justine Deperne, et al.. Spatio-temporal expression of the PagN Salmonella entry factor in the three commonly used murine models. International Symposium Salmonella and Salmonellosis (I3S), Jun 2022, Saint-Malo, France. ⟨hal-03730930⟩
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