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Updated: Aug 9, 2026
Chronic Salmonella Infected Mouse Model
Published on: May 31, 2010
Virulence-associated plasmids of Salmonella serotype Typhimurium in experimental murine infection
P Pardon1, M Y Popoff, C Coynault
1INRA, Centre de Tours-Nouzilly, Pathologie de la Reproduction, Monnaie, France.
Abstract:
The growth pattern of Salmonella enterica subsp. enterica serotype Typhimurium (Typhimurium) was studied in mice to examine the role of the 60-Mdal virulence-associated plasmid in the pathogenesis of mouse typhoid. After repeated subcultures at 45 degrees C, isogenic variants harbouring the virulence-associated plasmid (strains C52, TM122 and TM332) or having lost this large plasmid (strains C53, TM123 and TM333) were obtained from three parental strains (strains C5, TM12 and TM33, respectively). Plasmid pIP1350, present in strain C52, was tagged by Tn10 and transferred by successive conjugations to strains C53, TM123 and TM333. The behaviour of these three Typhimurium lines was studied in C57BL/6, DBA2, B6D2 (C57BL/6 X DBA2 F1 hybrid) and OF1 mice after oral infection, subcutaneous injection into the hind footpad or intravenous inoculation. The kinetics of organ colonization were followed at intervals after injection by enumeration of viable bacteria in caecum, mesenteric or popliteal lymph node, spleen, liver, kidney and lung depending on the route of infection. Strains harbouring virulence plasmid and their cured derivatives did not differ significantly in their ability to colonize caecal content and to translocate to draining lymph nodes. Elimination of the virulence plasmid was correlated with a significant reduction in the ability of cured variants to colonize spleen and liver. Reintroduction of the virulence plasmid into plasmidless variants restored the virulence to the level originally observed. These data demonstrate that a 60-Mdal plasmid in Typhimurium strains is necessary to ensure colonization of spleen and liver of experimentally infected mice.
Insights
The 60-Mdal virulence plasmid in Salmonella Typhimurium is crucial for colonizing mouse spleen and liver. Losing this plasmid significantly reduces virulence, while its reintroduction restores it, highlighting its role in pathogenesis.
Area of Science:
- Microbiology
- Pathogenesis
- Bacterial Genetics
Background:
- Salmonella enterica subsp. enterica serotype Typhimurium (Typhimurium) causes mouse typhoid.
- Virulence-associated plasmids play a key role in bacterial pathogenesis.
- The specific contribution of the 60-Mdal plasmid to Typhimurium virulence in mice was unclear.
Purpose of the Study:
- To investigate the role of the 60-Mdal virulence-associated plasmid in the pathogenesis of Salmonella Typhimurium in mice.
- To determine the necessity of this plasmid for bacterial colonization and survival in host organs.
Main Methods:
- Generated isogenic Typhimurium variants with and without the 60-Mdal virulence plasmid.
- Tagged and transferred the virulence plasmid (pIP1350) between strains.
- Infected various mouse strains (C57BL/6, DBA2, B6D2, OF1) via oral, subcutaneous, or intravenous routes.
- Quantified bacterial loads in multiple organs (caecum, lymph nodes, spleen, liver, kidney, lung) over time.
Main Results:
- Strains with and without the plasmid showed similar colonization of the caecum and translocation to lymph nodes.
- Elimination of the virulence plasmid significantly reduced bacterial colonization of the spleen and liver.
- Reintroduction of the plasmid restored the virulence of plasmidless strains.
Conclusions:
- The 60-Mdal virulence plasmid is essential for Salmonella Typhimurium to effectively colonize the spleen and liver in experimentally infected mice.
- This plasmid is a critical factor in the pathogenesis of mouse typhoid, specifically for systemic spread and organ colonization.
