Toxoplasmosis: a parasite that squirms to invade a host cell

Researchers at the CNRS, Inserm and Université Grenoble Alpes have just deciphered the mechanisms deployed by the parasite Toxoplasma gondii to penetrate the cells of its hosts. Using high-speed, high-resolution quantitative imagery, they have identified a peculiar movement of the parasite that allows it to close behind the door it has created to enter the host cell and nestle there. . This work, at the interface of cell biology, parasitology and biophysics, was published in the specialized journal "Cell Host & Microbes" of June 28, 2018.

Toxoplasmosis is a widespread infection caused by parasite, named Toxoplasma gondii, whose growth within a host is accompanied by irreversible tissue damage. Human contamination is mainly through the ingestion of undercooked meats or poorly washed fruits and vegetables. After having infected the digestive system, it gains the deep tissues of the nervous system, for example, persists there almost incognito and develops there

To do this, T. gondii has set up an ingenious invasive strategy. Scientists from the Institute for the Advancement of Biosciences (CNRS / Inserm / Université Grenoble Alpes) have succeeded in reconstructing the stages of penetration of the parasite into a host cell. T.gondii injects into the membrane of a cell, a complex of proteins forming a door through which it engulfs in a few seconds. He finally turns on himself to close the door behind him. The rotational force also allows him to isolate himself in a vacuole, a small pocket that serves as a nest where he continues to develop at the expense of his host.

This pioneering study in his field unveils one of the stages of the invasion that would likely be one of the first "signals" for Toxoplasma gondii, indicating that it can initiate the intracellular phase of its cycle. The team now seeks to understand in detail the mechanical properties of this gate that opens and closes the cell membranes.

The parasite, once returned to the cell , makes a rotation that allows him to close the door he had opened.
This movement also isolates him in a vacuole, a pocket where he will nest to continue to develop.

Credit / Source: Toxoplasma parasite twisting motion mechanically induces host cell membrane fission to complete invasion within a vacuole protective. Georgios Pavlou, Mateusz Biesaga, Bastien Touquet, Vanessa Lagal, Martial Balland, Alexandre Dufour, Mohamed-Ali Hakimi and Isabelle Tardieux. Cell Host & Microbes, June 2018. DOI: 10.1016 / j.chom.2018.06.003