Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium

ABSTRACT To establish a replicative niche during its infectious cycle between the intestinal lumen and tissue, the enteric pathogen Salmonella enterica serovar Typhimurium requires numerous virulence genes, including genes for two type III secretion systems (T3SS) and their cognate effectors. To bet...

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Autores principales:	Richard C. Laughlin, Leigh A. Knodler, Roula Barhoumi, H. Ross Payne, Jing Wu, Gabriel Gomez, Roberta Pugh, Sara D. Lawhon, Andreas J. Bäumler, Olivia Steele-Mortimer, L. Garry Adams
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Lenguaje:	EN
Publicado:	American Society for Microbiology 2014
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/94dff99ddb174ca8b1dc25b22ff70775
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spelling	oai:doaj.org-article:94dff99ddb174ca8b1dc25b22ff707752021-11-15T15:45:10ZSpatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium10.1128/mBio.00946-132150-7511https://doaj.org/article/94dff99ddb174ca8b1dc25b22ff707752014-02-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00946-13https://doaj.org/toc/2150-7511ABSTRACT To establish a replicative niche during its infectious cycle between the intestinal lumen and tissue, the enteric pathogen Salmonella enterica serovar Typhimurium requires numerous virulence genes, including genes for two type III secretion systems (T3SS) and their cognate effectors. To better understand the host-pathogen relationship, including early infection dynamics and induction kinetics of the bacterial virulence program in the context of a natural host, we monitored the subcellular localization and temporal expression of T3SS-1 and T3SS-2 using fluorescent single-cell reporters in a bovine, ligated ileal loop model of infection. We observed that the majority of bacteria at 2 h postinfection are flagellated, express T3SS-1 but not T3SS-2, and are associated with the epithelium or with extruding enterocytes. In epithelial cells, S. Typhimurium cells were surrounded by intact vacuolar membranes or present within membrane-compromised vacuoles that typically contained numerous vesicular structures. By 8 h postinfection, T3SS-2-expressing bacteria were detected in the lamina propria and in the underlying mucosa, while T3SS-1-expressing bacteria were in the lumen. Our work identifies for the first time the temporal and spatial regulation of T3SS-1 and -2 expression during an enteric infection in a natural host and provides further support for the concept of cytosolic S. Typhimurium in extruding epithelium as a mechanism for reseeding the lumen. IMPORTANCE The pathogenic bacterium Salmonella enterica serovar Typhimurium invades and persists within host cells using distinct sets of virulence genes. Genes from Salmonella pathogenicity island 1 (SPI-1) are used to initiate contact and facilitate uptake into nonphagocytic host cells, while genes within SPI-2 allow the pathogen to colonize host cells. While many studies have identified bacterial virulence determinants in animal models of infection, very few have focused on virulence gene expression at the single-cell level during an in vivo infection. To better understand when and where bacterial virulence factors are expressed during an acute enteric infection of a natural host, we infected bovine jejunal-ileal loops with S. Typhimurium cells harboring fluorescent transcriptional reporters for SPI-1 and -2 (PinvF and PssaG, respectively). After a prescribed time of infection, tissue and luminal fluid were collected and analyzed by microscopy. During early infection (≤2 h), bacteria within both intact and compromised membrane-bound vacuoles were observed within the epithelium, with the majority expressing SPI-1. As the infection progressed, S. Typhimurium displayed differential expression of the SPI-1 and SPI-2 regulons, with the majority of tissue-associated bacteria expressing SPI-2 and the majority of lumen-associated bacteria expressing SPI-1. This underscores the finding that Salmonella virulence gene expression changes as the pathogen transitions from one anatomical location to the next.Richard C. LaughlinLeigh A. KnodlerRoula BarhoumiH. Ross PayneJing WuGabriel GomezRoberta PughSara D. LawhonAndreas J. BäumlerOlivia Steele-MortimerL. Garry AdamsAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 5, Iss 1 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Richard C. Laughlin Leigh A. Knodler Roula Barhoumi H. Ross Payne Jing Wu Gabriel Gomez Roberta Pugh Sara D. Lawhon Andreas J. Bäumler Olivia Steele-Mortimer L. Garry Adams Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
description	ABSTRACT To establish a replicative niche during its infectious cycle between the intestinal lumen and tissue, the enteric pathogen Salmonella enterica serovar Typhimurium requires numerous virulence genes, including genes for two type III secretion systems (T3SS) and their cognate effectors. To better understand the host-pathogen relationship, including early infection dynamics and induction kinetics of the bacterial virulence program in the context of a natural host, we monitored the subcellular localization and temporal expression of T3SS-1 and T3SS-2 using fluorescent single-cell reporters in a bovine, ligated ileal loop model of infection. We observed that the majority of bacteria at 2 h postinfection are flagellated, express T3SS-1 but not T3SS-2, and are associated with the epithelium or with extruding enterocytes. In epithelial cells, S. Typhimurium cells were surrounded by intact vacuolar membranes or present within membrane-compromised vacuoles that typically contained numerous vesicular structures. By 8 h postinfection, T3SS-2-expressing bacteria were detected in the lamina propria and in the underlying mucosa, while T3SS-1-expressing bacteria were in the lumen. Our work identifies for the first time the temporal and spatial regulation of T3SS-1 and -2 expression during an enteric infection in a natural host and provides further support for the concept of cytosolic S. Typhimurium in extruding epithelium as a mechanism for reseeding the lumen. IMPORTANCE The pathogenic bacterium Salmonella enterica serovar Typhimurium invades and persists within host cells using distinct sets of virulence genes. Genes from Salmonella pathogenicity island 1 (SPI-1) are used to initiate contact and facilitate uptake into nonphagocytic host cells, while genes within SPI-2 allow the pathogen to colonize host cells. While many studies have identified bacterial virulence determinants in animal models of infection, very few have focused on virulence gene expression at the single-cell level during an in vivo infection. To better understand when and where bacterial virulence factors are expressed during an acute enteric infection of a natural host, we infected bovine jejunal-ileal loops with S. Typhimurium cells harboring fluorescent transcriptional reporters for SPI-1 and -2 (PinvF and PssaG, respectively). After a prescribed time of infection, tissue and luminal fluid were collected and analyzed by microscopy. During early infection (≤2 h), bacteria within both intact and compromised membrane-bound vacuoles were observed within the epithelium, with the majority expressing SPI-1. As the infection progressed, S. Typhimurium displayed differential expression of the SPI-1 and SPI-2 regulons, with the majority of tissue-associated bacteria expressing SPI-2 and the majority of lumen-associated bacteria expressing SPI-1. This underscores the finding that Salmonella virulence gene expression changes as the pathogen transitions from one anatomical location to the next.
format	article
author	Richard C. Laughlin Leigh A. Knodler Roula Barhoumi H. Ross Payne Jing Wu Gabriel Gomez Roberta Pugh Sara D. Lawhon Andreas J. Bäumler Olivia Steele-Mortimer L. Garry Adams
author_facet	Richard C. Laughlin Leigh A. Knodler Roula Barhoumi H. Ross Payne Jing Wu Gabriel Gomez Roberta Pugh Sara D. Lawhon Andreas J. Bäumler Olivia Steele-Mortimer L. Garry Adams
author_sort	Richard C. Laughlin
title	Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
title_short	Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
title_full	Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
title_fullStr	Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
title_full_unstemmed	Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium
title_sort	spatial segregation of virulence gene expression during acute enteric infection with <named-content content-type="genus-species">salmonella enterica</named-content> serovar typhimurium
publisher	American Society for Microbiology
publishDate	2014
url	https://doaj.org/article/94dff99ddb174ca8b1dc25b22ff70775
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Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with <named-content content-type="genus-species">Salmonella enterica</named-content> serovar Typhimurium

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