HtpG and STM4067 contribute to long-term Salmonella Typhimurium persistence in pigs

Persistent Salmonella Typhimurium infections in pigs often result in asymptomatic carrier pigs and are a major concern for food safety and human health. Tonsils and lymph nodes play a key role in the persistence of Salmonella Typhimurium in pigs, but very little is known about the underlying mechanisms. After bacterial invasion in pigs, the porcine immune system will respond to clear the Salmonella infection and bacterial survival strategies for (long-)term persistence will become important. For the identification of Salmonella Typhimurium genes specifically induced in tonsils and lymph nodes at 3 weeks post inoculation, a genome-wide screening method was performed using in vivo expression technology (IVET). Using IVET we were able to identify different Salmonella Typhimurium genes that play a role in long-term persistence in pigs. Furthermore, we were able to show a role for Salmonella Typhimurium genes htpG (encoding a heat-shock protein) and STM4067 (encoding a protein with an unknown function) in long-term persistence in the porcine intestines and lymph nodes, although their exact role remains to be clarified