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Paralysed parasites

Researchers at Heidelberg University Hospital have discovered a protein that is vital for the toxoplasmosis pathogen. This quite common infectious disease, which is mainly transferred to humans from cats, is especially dangerous for pregnant women as it can harm an unborn child.

Laboratory experiments have shown that if the pathogen's dynamin B protein does not function properly, it can no longer infect human cells because the parasite is unable to develop the organelles required for the invasion and modulation of the host cell. The researchers' findings not only provide insights into the replication cycle of the small parasites (about 15 micrometres long), but might also present a new target in the fight against toxoplasmosis.

The researchers have been able to show that the protein is also present in the malaria pathogen (plasmodium). Every year, this disease claims the lives of several million people. "We will now investigate the function of dynamin B in the malaria pathogen in greater detail in order to find out whether it could represent a new starting point for the development of new anti-malaria drugs," said Dr. Markus Meissner, laboratory manager at Heidelberg University Hospital's Department of Hygiene.

The paper written by Meissner's team, which includes his PhD student Manuela Breinich, has been published in the internationally renowned journal Current Biology (prepublished online). The project was backed by BioFuture competition funds through the German Federal Ministry of Education and Research. BioFuture is one of the BMBF's most successful initiatives and its objective is to recruit excellent junior researchers for science and industry in the area of biotechnology.

Dynamin B is essential for correct protein transport

The unicellular parasite Toxoplasma gondii invades human cells where it then replicates. It then leaves the host cell in order to infect further cells. The researchers have succeeded in engineering a T. gondii mutant where the function of dynamin B is permanently impaired. They found that dynamin B is required by the parasite to transport important proteins - a major prerequisite for the parasite to be able to leave the host cell and invade new cells. The mutant parasites are able to replicate but are unable to escape from or invade new cells, remaining instead in a kind of paralysis.

Microscopic view into the toxoplasmosis pathogen: functional dynamin B (green) enables the transport of important protein (red) to targeted places within the parasite where essential cell structures are formed (left). Non-functional dynamin B leads to the generation of defective cell structures which prevents the parasite from escaping from or invading cells.
Microscopic view into the toxoplasmosis pathogen: functional dynamin B (green) enables the transport of important protein (red) to targeted places within the parasite where essential cell structures are formed (left). Non-functional dynamin B leads to the generation of defective cell structures which prevents the parasite from escaping from or invading cells. © Dept. of Hygiene, University of Heidelberg

Infection during pregnancy is dangerous

Toxoplasmosis is a common infectious disease caused by the parasite Toxoplasma gondii. It can affect people of all ages. The majority of infections go unnoticed and do not lead to symptoms in otherwise healthy people. However, T. gondii infections during pregnancy are dangerous because they can lead to miscarriage or deformation in the unborn child. People with a weakened immune system may become seriously ill.

Cats have been shown to be a major carrier of this pathogen; faeces of a recently infected cat pose the greatest risk of infection, during such activities as gardening for example or through food that is contaminated by cat faeces (vegetables, fruit). The consumption of insufficiently heated or raw meat might also lead to infection.

Website address: https://www.gesundheitsindustrie-bw.de/en/article/press-release/paralysed-parasites