Scientists discover how typhoid bacterium causes DNA breakage

A team of researchers at the University of Sheffield studied how the pathogen Salmonella typhi, which causes typhoid, accelerates the aging of body cells by “hijacking” molecules for DNA repair.

Typhoid fever, also known as “typhus,” affects more than 21 million people worldwide each year, killing about 168,000 people. The disease is particularly widespread in Southeast Asia.

Researchers have infected human cells with Salmonella typhi in the laboratory and used fluorescent microscopes to understand how this pathogen damaged DNA. They then discovered that it induced a particular form of damage to the DNA itself by taking control of DNA repair machines and making cells more susceptible to infection, in practice accelerating their aging.

DNA repair “machines” are molecules inside the cells that constantly protect our DNA when it is threatened by environmental factors such as ultraviolet light or smoke. By attacking these molecules, the typhoid pathogen causes serious damage that damages cellular DNA.

Daniel Humphreys, one of the authors of the study, comments on the results: “Our results have shown that pathogenic bacteria can accelerate cell aging through a toxin and take advantage of it to establish infections. This makes sense because infections are often more difficult to fight and recover as we age, which is partly due to cellular aging, but the fact that bacterial pathogens affect this phenomenon was unexpected.”

Another author of the study, Sherif El-Khamisy, a researcher at the Healthy Lifespan Institute at the University of England, comments: “Until now, how Salmonella typhi’s typhoid toxin contributed to the infection was a mystery. If we want to fight typhoid, understanding how the toxin causes breakage in the DNA of human cells and promotes infection is key and we hope this discovery will be the first step in developing new strategies to control typhoid, which affects some of the most vulnerable communities in the world.”

Researcher Angela Ibler was also involved in the research.


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