When it comes to the malaria parasite Plasmodium, scientists are confronted with many questions they still have not been able to answer. Friedrich Frischknecht and his research group from the Center of Infectious Diseases at the Heidelberg University Hospital are now using innovative methods to uncover its secrets. The have filmed the single-cell parasite during its “birth” in the mosquito, while it circles blood vessels and in an artificial labyrinth with poles. Their findings have now been published in eLife and Advanced Healthcare Materials.
PhD student Dennis Klug discovered that plasmodia can only emerge from oocysts in a joint effort. Responsible for the egress is a protein called TRP1. Klug and Frischknecht compared parasites with and without TRP1 and their films show that the parasites with the protein start twirling uniformly after the development in the oocyst is finalized. The movement seems to have a strong effect on the cystic wall – it bursts and sets the parasites free. Without TRP1, they don’t even start moving. According to Frischknecht “this could indicate that TRP1 functions like a sensor that tells the parasite to start moving.”
Malaria parasites inside an oocyst
But why are malaria parasites bent?
The scientists suspect that this riddle is tightly connected to the question of how the parasites reach the blood vessels in the skin. The Plasmodia have the shape of a half-moon and mostly move in circles. “The diameter of this circle is equal to that of the smallest blood vessels in the skin”, says Frischknecht. He is convinced that this is not a coincidence. In cooperation with CellNetworks member Prof. Dr. Joachim Spatz, his team built a microscopically small pole labyrinth for the single-cell organisms. The poles had different diameters and were supposed to represent blood vessels. The result of their studies: The parasites preferred those poles that matched their curve. “It looks as if they are actually built to circle the fine blood vessels of the skin”, concludes Frischknecht whose team was able to film the movements. “This would explain how they are able to find the weak spots to invade the vessels.” His research group will address this and other questions in the context of SFB 1129.
Publications with the films
Klug and Frischknecht, Motility precedes egress of malaria parasites from oocysts, eLife, 2017.
Muthinja, Ripp, Hellmann, Haraszti, Dahan, Lemgruber, Battista, Schütz, Fackler, Schwarz, Spatz and Frischknecht, Microstructured blood vessel surrogates reveal structural tropism of motile malaria parasites, Advanced Healthcare Materials, 2017.
Prof. Dr. Friedrich Frischknecht
Department of Parasitology
Center for Infectious Diseases
Heidelberg University Hospital
Tel +49 6221 56-6537