Wednesday 24 September 2014

H. pylori bacteria mutate to establish infection

Rapid evolution allows Helicobacter pylori, the bacterium that causes ulcers in humans, to evade the immune system during the early, acute phase of infection. This finding complements earlier work that quantified how quickly H. pylori mutations accumulate during chronic infection. During the acute phase, mutational rates are 30 to 50 times greater than during the chronic phase.

The burst in mutations was discovered by researchers at Penn State, the University of Western Australia, and the University of California, Davis. These researchers showed, for the first time and in real time, the interplay between the human immune system and invading bacteria that allows the bacteria to counter the immune system by quickly evolving. The researchers published their results June 13 in Nature Communications, in an article entitled “A mutation burst during the acute phase of Helicobacter pylori infection in humans and rhesus macaques.”

To trace H. pylori infections in human patients, the researchers used a next-generation sequencing approach. As the researchers indicated in their article, they analyzed “the rate and pattern of genome evolution in H. pylori from the genomes of two input strains isolated from human volunteers with asymptomatic infection, and the genomes of two output strains collected 20 and 44 days after re-infection.”

Whether bacteria other than H. pylori undergo a similar burst of accelerated evolution immediately after infection is not yet known, but the team plans to investigate other common human pathogens in future research.

For further details, see: Nature

Posted by Tim Sandle

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