06 July 2016 - PRESS RELEASE

Helicobacter pylori: a gastric pathogen capable of genetic transformation

DZIF scientists at the MHH have deciphered the rapid transformation of Helicobacter pylori, a pathogen which causes gastric cancer.

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Focus on Helicobacter (from left): Dr Florent Ailloud, Prof Sebastian Suerbaum and Iratxe Estibariz© MHH/Kaiser

Helicobacter pylori, a bacterium which causes gastric cancer, can adapt to humans: it can vary its genes during the course of infection like no other bacterium. In collaboration with Dr Xavier Didelot, statistics expert from the Imperial College in London, scientists at the Hannover Medical School (MHH) and the German Center for Infection Research (DZIF) have found out the reason for this high variability: two gene fragment integration mechanisms that cause the bacteria to undergo genetic exchange, similar to that of sexually reproducing organisms.

Two different Helicobacter pylori bacteria had already been known to exchange DNA fragments on encountering each other in the stomach. It has now been shown that this high individuality occurs as a result of two mechanisms that lead to the integration of gene fragments of different lengths. The integration of very short gene snippets, consisting of less than 50 base pairs, gives the bacteria an extremely high variability within the genes. The integration of longer DNA fragments, with an average of 1,600 base pairs, ensures consistency and provides the option of exchanging entire genes. “The effect of this genetic exchange is actually similar to that of sexually reproducing organisms,” says DZIF Professor Sebastian Suerbaum, Head of the MHH Institute for Medical Microbiology and Hospital Epidemiology. Together with his team, he wants to elucidate the underlying molecular mechanisms.

Helicobacter pylori’s high genetic variability is also considered to be an important obstacle for developing a vaccine against the pathogen. These findings are an important motivation for the researchers. Their work is being funded by German Center for Infection Research (DZIF) and the Collaborative Research Center (SFB) 900.

Publication

Bubendorfer S, Krebes J, Yang I, Hage E, Schulz TF, Bahlawane C, Didelot X, Suerbaum S:
Genome-wide analysis of chromosomal import patterns after natural transformation of Helicobacter pylori.
Nat Commun. 2016 Jun 22;7:11995. doi: 10.1038/ncomms11995

MHH Press Release (German)



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