Study: How Salmonella Might Evade Our Immune Systems

A new study from the University of Pennsylvania reveals how some Salmonella bacteria are able to evade our immune systems, allowing them to cause a systemic infection.  The researchers — led by Igor Brodsky, an assistant professor of pathobiology at the School of Veterinary Medicine — hypothesized that Salmonella might have some way of avoiding the activation of inflammasomes, a complex of proteins that detects pathogens and releases signaling molecules to recruit other elements of the immune system to fight them off.  They studied strains of Salmonella with a mutated gene responsible for encoding an enzyme called aconitase and found that this mutation led to a highly activated inflammasome.  The researchers also infected mice with this mutated Salmonella, and the animals cleared the infection.  Members of the team think that normal aconitase might do the opposite — inhibit the inflammasome and promote systemic Salmonella virulence.  Brodsky is also working with his colleagues to develop a vaccine for chickens to protect them against systemic Salmonella infections. This work may incorporate an aconitase mutant.  “We get Salmonella from chickens that are chronically infected,” Brodsky said, “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 inflammasome study was recently published in the Journal of Experimental Medicine.