Health versus disease: an evolutionary arms race
Kiel scientists present a new study on the coevolution between host and pathogens. Their results not only shed a new light on evolutionary dynamics, but may also lead to more sustainable treatment strategies in the future.
Microscopic photograph of the threadworm Caenorhabditis elegans with the red-stained bacteria inside it. Foto: Andrei Papkou, Hinrich Schulenburg, Kiel University
The research team of Professor Hinrich Schulenburg, member of the research focus “Kiel Life Science”, used a special experimental model system, consisting of the nematode worm Caenorhabditis elegans as a host and the bacterium Bacillus thuringiensis as a pathogen, to follow evolution in real-time. The core of the study was an evolution experiment under controlled conditions in the lab, which was combined with the characterization of the evolved genetic mechanisms and specific traits in both the worm and the bacterium. “We were able to precisely control the extent of the mutual adaptations and thus the coevolution in the lab. This provided us with the ultimate test to find out what really happens during coevolution be tween host and pathogen,” emphasizes Schulenburg.
The research relied on a fruitful collaboration between the Schulenburg lab and research groups at the Institute of Clinical Molecular Biology (ICMB) at Kiel University and at the universities of Münster, Göttingen, Osnabrück and Tübingen, and yielded two important new insights: the first is that virulence and thus the ability of the pathogen to damage or kill the host only provides an evolutionary advantage during coevolution. Dr Leila Masri, former member of the Schulenburg Lab and now postdoctoral researcher at the Institute of Science and Technology Austria, explains: “We were astonished that virulence is only maintained when there is the corresponding evolutionary counter-response of the host, so that an evolutionary arms race occurs.”
Further research is still required before the current findings can be applied to human disease. They may nevertheless suggest that an increase in selective pressure on the pathogen can enhance its harmful potential. The increased use of antibiotics, for example, promotes the spread of resistant pathogens and ultimately aggravates disease progression. The Kiel researchers are convinced that a different strategy is worth consideration: Instead of aiming at pathogen elimination, it may be more efficient to promote tolerance of the host to the disease agent. This could prevent an escalating arms race on the pathogen side and thus represent a more sustainable treatment strategy to cope with infectious disease.
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