The Toxoplasma parasite is carried by a large part of the world’s human population. Now, a study by researchers at Stockholm University shows how this microscopic parasite spreads so successfully in the body, for example in the brain. The parasite infects immune cells and hijacks their identity. The study is published in the scientific journal Cell Host & Microbe.
In order to fight against infections, the different roles of immune cells in the body are very strictly regulated. Scientists have long wondered how Toxoplasma manages to infect so many people and animal species and spread so efficiently.
“We have now discovered a protein that the parasite uses to reprogram the immune system,” says Arne ten Hoeve, a researcher in the Department of Molecular Biosciences at the Wenner-Gren Institute at Stockholm University.
The study shows that the parasite injects the protein into the nucleus of the immune cell and thus changes the identity of the cell. The parasite tricks the immune cell into thinking it is another type of cell. This alters the expression of genes and the behavior of the immune cell. Toxoplasma causes infected cells that normally should not travel through the body to move very quickly and in this way the parasite spreads to different organs.
The phenomenon has been described as Toxoplasma turning immune cells into roaming Trojan horses or “zombies” that spread the parasite. The recently published study provides a molecular explanation for the phenomenon and also shows that the parasite is much more targeted in its spread than previously thought.
“It is amazing that the parasite is able to hijack the identity of immune cells in such a clever way. We believe the results may explain why Toxoplasma spreads so efficiently through the body when infecting humans and animals,” says Professor Antonio Barragan, who led the study, which was carried out in collaboration with French and American researchers.
Arne L. ten Hoeve, Laurence Braun, Matias E. Rodriguez, Gabriela C. Olivera, Alexandre Bougdour, Lucid Belmudes, Yohann Couté, Jeroen PJ Saeij, Mohamed-Ali Hakimi, Antonio Barragan DOI:10.1016/j.chom.2022.10.001