Sleeping sickness parasite masters three different swimming modes

Scientists from Germany and Switzerland decipher the precise patterns of motion of the parasite Trypanosoma.

June 16, 2011

The causative agent of African sleeping sickness, annually responsible for several thousands of deaths in Africa and South America, is a motile cell: it propels itself through its host’s bloodstream until – in the last stage of the disease – it overcomes the blood-brain-barrier and penetrates its victim’s brain. In order to fight this deadly disease, scientists are trying to understand the parasite’s exact patterns of movement. Researchers from the Max Planck Institute for Dynamics and Self-Organization (MPIDS) in Germany as well as from the Universities of Würzburg, Göttingen and Basel have now succeeded in identifying three different swimming modes. In addition, they were able to show for the first time, that these swimming modes correspond to the shape and stiffness of the parasite.

Top: The randomly tumbling Trypanosoma have a more bent shape pointing to a more flexible body. Bottom: The directional swimmers have a stretched form indicating that they are stiffer.

A reason for these anatomical differences within a single population of Trypanosoma is yet unclear. “It is possible, that they stand for different phases within the parasite’s life cycle”, says Thomas Pfohl from the University of Basel. The directional motion could belong to the last phase, when the agent drills itself into its victim’s tissue. Another explanation could be that when looking for food, the cells choose the directional swimming strategy.

A few years ago, the researchers from Würzburg together with their colleagues from MPIDS discovered that swimming quickly helps the Trypanosomae avoid host antibodies. The current that passes along the parasites’ smooth surface pulls the antibodies downstream into the direction of the cell mouth, where they are then “eaten”. In a next step, the scientists now want to study which swimming mode is especially favourable for this survival strategy. “Possibly, the tumbling Trypanosoma are more vulnerable than their streamlined colleagues”, says Pfohl. A precise understanding of these motions could therefore help find a starting point for fighting the parasites systematically.


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