ROP39 is an Irgb10-specific parasite effector that modulates acute Toxoplasma gondii virulence

• Published in: PLoS pathogens Vol. 19; no. 1; p. e1011003
• Main Authors: Singh, Shishir, Murillo-León, Mateo, Endres, Niklas Sebastian, Arenas Soto, Ailan Farid, Gómez-Marín, Jorge Enrique, Melbert, Florence, Kanneganti, Thirumala-Devi, Yamamoto, Masahiro, Campos, Claudia, Howard, Jonathan Charles, Taylor, Gregory Alan, Steinfeldt, Tobias
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01-01-2023; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Biological response modifiers; Biology and Life Sciences; Cats; Control; Cysts; Deactivation; Distribution; Domestic animals; Equilibrium; G proteins; GTP Phosphohydrolases - metabolism; Guanosine triphosphatase; Health aspects; Human populations; Humans; In vivo methods and tests; Inactivation; Infection; Interferon; Kinases; Laboratories; Medicine and Health Sciences; Mice; Parasites; Parasites - metabolism; Physical Sciences; Proteins; Protozoa; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; Research and Analysis Methods; Testing; Toxoplasma; Toxoplasma - metabolism; Toxoplasma gondii; Toxoplasmosis; Virulence; Virulence (Microbiology); Germany
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1011003

Toxoplasma gondii (T. gondii) is a zoonotic apicomplexan parasite that is an important cause of clinical disability in humans. On a global scale, one third of the human population is infected with T. gondii. Mice and other small rodents are believed to be responsible for transmission of T. gondii to the domestic cat, its definitive host. Interferon-inducible Immunity-Related GTPases (IRG proteins) are important for control of murine T. gondii infections. Virulence differences between T. gondii strains are linked to polymorphic rhoptry proteins (ROPs) that cooperate to inactivate individual IRG family members. In particular, the pseudokinase ROP5 isoform B is critically important in laboratory strains of mice. We identified T. gondii ROP39 in complex with ROP5B and demonstrate its contribution to acute T. gondii virulence. ROP39 directly targets Irgb10 and inhibits homodimer formation of the GTPase leading to an overall reduction of IRG protein loading onto the parasitophorous vacuolar membrane (PVM). Maintenance of PVM integrity rescues the parasite from IRG protein-mediated clearance in vitro and in vivo. This study identifies a novel T. gondii effector that is important for specific inactivation of the IRG resistance system. Our data reveal that yet unknown T. gondii effectors can emerge from identification of direct interaction partners of ROP5B.