Modulation of innate immunity by Toxoplasma gondii virulence effectors

The intracellular parasiteToxoplasma gondiican infect a range of hosts and occasionally causes serious disease in humans. In this Review, Hunter and Sibley summarize recent studies that implicate rhoptry kinases and a dense-granule protein as mediators of acute virulence in the mouse model. They also describe the complex interplay between these parasite effector proteins and the innate immune system. Toxoplasma gondii is a common parasite of animals and humans and can cause serious opportunistic infections. However, the majority of infections are asymptomatic, possibly because the organism has co-evolved with its many vertebrate hosts and has developed multiple strategies to persist asymptomatically for the lifetime of the host. Over the past two decades, infection studies in the mouse, combined with forward-genetics approaches aimed at unravelling the molecular basis of infection, have revealed that T. gondii virulence is mediated, in part, by secretion of effector proteins into the host cell during invasion. Here, we review recent advances that illustrate how these virulence factors disarm innate immunity and promote survival of the parasite.