ROP39 modulates Toxoplasma gondii virulence

What is it about?

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii (T. gondii), is an obligate intracellular food-borne parasite. It has a very broad host range establishing a productive infection in virtually all warm- blooded animals including humans. A mouse model of toxoplasmosis is of medical importance because the relationship with one of its most important natural hosts, the mouse, determines the impact of T. gondii infections in humans. In the acute phase of infection, the parasite seeks to reach an intermediate level of virulence to increase chances for transmission. Virulence is a multifactorial phenotype; we and others have described several effector proteins of the parasite that specifically inhibit certain host cell GTPases (IRG proteins). Only the combination of all parasite effectors determines the full virulence potential of the parasite. Here, we demonstrate that T. gondii has evolved a virulence effec- tor, ROP39, that specifically targets Irgb10 to escape IRG-mediated control. This is a novel aspect of the infection biology of this world-wide zoonotic pathogen. It advances our understanding of the coevolutionary relationship of T. gondii and the mouse, an important intermediate host for transmission.

Featured Image

Why is it important?

Our data provide additional insight into the interplay between host cell resistance GTPases and T. gondii virulence effectors and reveal that novel effectors of the parasite can emerge from identification of interaction partners of ROP5. The complex dynamics between these two systems of parasite virulence and host cell resistance documents the coevolutionary relationship of T. gondii and Mus musculus, an important inter- mediate host for transmission.