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Helicobacter pylori bacteria The chameleon in the stomach
About 40 percent of people in this country are chronically infected with Helicobacter pylori. This is a type of bacteria that colonize the gastric mucosa and thereby may cause stomach ulcers. In addition, Helicobacter pylori infestation leads to an increased risk of gastric cancer. The special feature of the germ is its rapid adaptability to humans, making it as individual as a fingerprint. Scientists at the Hannover Medical School (MHH) have now discovered the reason for this extraordinary variability in collaboration with a statistics expert from Imperial College in London. The researchers published their findings in the journal Nature Communications.
Frequently, acute gastritis first occurs
About every fourth adult human in Germany is infected with the stomach bacterium Helicobacter pylori (H. pylori for short), which lives on and within the gastric mucosa. Accordingly, the first sign of infection is often acute gastritis, which may progress to chronic inflammation and lead to a range of problems. Possible here are e.g. Stomach complaints or ulcers in the stomach and duodenum, also apply H. pylori as the cause of most gastric cancers. A study carried out by Swiss researchers recently showed that in patients treated with antibiotics a few hours after infection, the risk of gastric cancer was significantly reduced compared to untreated individuals.
Helicobacter pylori are extremely adaptable. Why this is so, scientists have now found out from Hannover. (Image: Dr_Kateryna / fotolia.com) Bacteria exchange DNA fragments when they meet in the stomach
The extraordinary thing about the pathogen is its variability. Because like no other bacterium it changes its genes in the course of the infection, whereby it can adapt itself exactly to humans. Now scientists of the Hannover Medical School (MHH) in cooperation with the statistics expert Dr. med. Xavier Didelot from Imperial College in London found out the reason for this unique adaptability of the "chameleon" in the stomach.
According to a recent communication from the MHH, it was already known before the Hanover study that two different Helicobacter pylori bacteria exchange DNA fragments when they meet in the stomach. However, it has now been shown that the great individuality is due to two specific uptake mechanisms, which lead to fragments of different lengths being integrated. "The uptake of very short gene clots, which are less than 50 base pairs long, allows the bacteria an extremely high variability within the genes. The inclusion of longer, averaging 1,600 base pairs, pieces of DNA ensures consistency and the ability to exchange entire genes, "said Professor. Sebastian Suerbaum quoted in the college's report. "The effect of the genetic exchange even resembles that which takes place in sexually reproducing organisms," continues the head of the MHH Institute of Medical Microbiology and Hospital Hygiene.
Variability complicates the development of a vaccine
Now, Suerbaum and his team want to explore the underlying molecular mechanisms, the university reports. However, they have already discovered a discovery: They recognize that many so-called "restriction enzymes" occur in Helicobacter pylori, which can recognize and cut foreign DNA at certain positions. The recorded pieces of DNA of other Helicobacter pylori bacteria, however, would be integrated into the genome independently of these enzymes. The problem is that it is precisely this large genetic variability that makes it difficult to develop a vaccine against this pathogen. (No)