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Over the past several years, bacteria have evolved many ways to specifically evade our innate immune system.

Researchers recently studied a bacteria called Salmonella, with similar traits and revealed how they manage to hide from the immune system and cause systemic infection. The findings of the study could help researchers craft a more effective vaccine against Salmonella. 

"Many of the same signals that are present in harmless bacteria are also present in pathogenic bacteria," said Igor Brodsky, an assistant professor in Penn Vet's Department of Pathobiology and senior author of the paper in the press release. "One of the big unanswered questions is how does the innate immune system distinguish between the two? And, conversely, how have pathogenic bacteria evolved to get around the immune response?"

"We hypothesized that during the systemic phase of disease, Salmonella would have some way of avoiding inflammasome activation," Brodsky said.

For identifying the mechanism, the team made a library of Salmonella mutants, aiming to find those who might be involved in the evasion strategy. Among those 18 genes, they found that four had been previously noted to have a role in enabling Salmonella strains to cause longterm, chronic infections. 

"That was interesting because it suggested that at least a subset of those genes that might be important for long-term infection might be involved in evading or suppressing the inflammasome response," Brodsky said.

"We get Salmonella from chickens that are chronically infected," Brodsky added, "so, if you could prevent or limit chronic infection of chickens, that would be a nice way to limit Salmonella in the food supply."

The study has been published in the Journal of Experimental Medicine.