Tissue-specific Salmonella Typhimurium gene expression during persistence in pigs

Area of Science:

• Veterinary Microbiology
• Bacterial Pathogenesis
• Zoonotic Diseases

Background:

• Salmonellosis, caused by Salmonella Typhimurium, is a significant bacterial zoonotic disease.
• Pigs act as asymptomatic carriers, posing a risk for pork contamination.
• Mechanisms of Salmonella Typhimurium persistence in pigs remain largely unknown.

Purpose of the Study:

• To identify Salmonella Typhimurium genes expressed during persistence in pigs.
• To understand tissue-specific gene expression patterns.
• To investigate the role of specific genes in Salmonella Typhimurium persistence.

Main Methods:

• In vivo expression technology (IVET) using a promoter-trap method.
• Oral inoculation of pigs with Salmonella Typhimurium.
• Analysis of gene expression in tonsils, ileum, and ileocaecal lymph nodes.
• Construction and testing of gene deletion mutants (ΔSTM4067, ΔsifB).

Main Results:

• 37 Salmonella Typhimurium genes were identified as expressed during persistence.
• efp and rpoZ genes showed specific expression in ileocaecal lymph nodes.
• STM4067 deletion significantly reduced Salmonella Typhimurium persistence in multiple pig tissues and feces.
• Deletion of the SPI-2 effector gene sifB did not impact Salmonella Typhimurium persistence.

Conclusions:

• This study is the first to identify Salmonella Typhimurium genes expressed during pig persistence.
• efp and rpoZ are specifically expressed in ileocaecal lymph nodes, suggesting a role in persistence.
• STM4067 is identified as a key factor involved in Salmonella Typhimurium persistence in pigs.