New hope in the fight against cholera

Scientists pursue new treatment approach against cholera

Time and again there have been reports of large cholera epidemics with hundreds of thousands of people infected and thousands dead. Scientists have now discovered a completely new approach to fighting cholera. This is based on the recognition that the cholera pathogens have different effects on the gene activity in the stomach and intestine.

Cholera epidemics mainly affect countries with already weak infrastructure. The World Health Organization (WHO) recently reported the massive spread of cholera in Yemen, where nearly one million people became infected in 2017. The trigger is the bacterium Vibrio cholerae, which silences certain genes in the intestine in order to survive. This finding could also open up new approaches to treatment or prevention, say scientists from the Institute of Molecular Biosciences at the University of Graz.

Cholera bacteria easily dig into polluted drinking water. Scientists have now developed a new approach in the fight against the pathogens. (Image: Ezume Images / fotolia.com)

How do the pathogens adapt to their environment??

The bacterium Vibrio cholerae can survive in a wide range of conditions. In the environment, for example, it thrives in ponds, ponds or in the ocean, but the pathogens can multiply even under completely different conditions in the human intestine, explain the researchers. Professor Stefan Schild and colleagues from the Institute of Molecular Biosciences at the University of Graz have therefore investigated how the bacterium adapts to its respective environment. Using a special method, the scientists analyzed which genes in the host activate or deactivate the pathogens.

Which genes are switched off??

According to Prof. Schild, the method used to detect gene activation "was used to investigate, among other things, how the toxin is produced in the gut, which triggers diarrhea." The researchers have also developed a special technique to identify genes that have been switched off. For the genes that are eliminated by the pathogens, it has been shown that "the microorganisms not only (deactivate) those that they just do not need, but also those that even harm them under certain conditions," explains Prof. Schild. This is a potential target against the infectious disease, which has so far been largely ignored.

Bacteria must ensure their own survival

According to a report from the University of Graz, researchers were able to identify a factor in the mouse model that is particularly strongly suppressed. This is a so-called chloride ion transporter, which taps the energy source of the bacterium. The bacterium must switch it off in the intestine to ensure its own survival. At high pH levels in the environment - as is the case in the intestine - it is difficult for Vibrio cholerae to maintain its own supply anyway. "If the transporter remains active, the pathogen can not colonize the digestive tract due to lack of strength, and the disease does not come to an outbreak," continued Prof. Schild.

Deactivation of genes preventable?

In the stomach, the situation is different. Here, the bacterium still relies on the transporter, which is why this initially remains active. "If you could pretend to the bacteria that it is still in the stomach, it would prevent its spread in the gut," explains Professor Schild. The aim of further research is now to find out how the microorganism could be prevented from eliminating such genes in the gut. This fundamental idea of ​​specifically activating "silent" genetic factors can in principle be transferred to other infectious germs and thus opens up a new strategy for combating them, the researchers concluded. (Fp)