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Not your typical toxin – typhoid toxin increases host survival and promotes chronic asymptomatic infection

Genotoxins damage the genetic material in cells and can cause mutations and cancer. Some bacteria code for and produce genotoxins. A study published in PLOS Pathogens reports the surprising finding that one of them, typhoid toxin, actually increases survival of the infected host and promotes long-term colonization without causing disease in the host. The work, the authors say “poses the semantic and biological question of whether ‘toxin’ is the appropriate designation”.

DNA damage caused by bacterial genotoxins has been linked to cancer, but what, if any, function genotoxins have in the context of a natural infection is not clear. Teresa Frisan, from the Karolinska Institute in Stockholm, Sweden, and colleagues focused on the typhoid toxin from Salmonella enterica Typhi (S. Typhi), and specifically looked at chronic asymptomatic infection, which is known to increase the risk for tumors.

DNA damage following infection with the genotoxin-carrying Salmonella strain
DNA damage following infection with the genotoxin-carrying Salmonella strain
Image Credit: Del Bel Belluz et al.