Active cell invasion by Toxoplasma gondii leads to avoidance of phagocytic processing

Apicomplexan parasites are responsible for a large number of economically important diseases of humans and animals. Due to their extremely ancient evolutionary position, they display a variety of unusual adaptations for parasitism of eukaryotic hosts. They are able to glide along substrates using an actinomyosin motor for propulsion. Invasion occurs by the localized invagination of the host cell plasma membrane to form a unique intracellular vacuole. Entry is aided by the interaction of apically-released adhesins with host cell receptors which are then progressively capped to the posterior end of the parasite, thereby enveloping the parasite in a vacuole derived form the host cell plasma membrane. During penetration, the parasite secretes a variety of proteins involved in adhesion, vacuole formation, and modification of the intracellular compartment. The specialized intracellular compartments occupied by these parasites offers an intriguing window on eukaryotic cell biology that should be particularly insightful for understanding the control of exocytosis, protein-membrane associations, and membrane trafficking.