Review: Toxoplasma gondii cellular invasion.

Toxoplasma gondii, the etiologic agent of toxoplasmosis, is a ubiquitous protozoan parasite that requires an intracellular site for growth and replication. The invasive process involves six steps: a) cellular recognition, b) parasite movements by means of a subpellicular microtubule cytoskeleton, c) cell to cell adhesion, d) rhoptry secretion of penetrating enhancing factor (PEF) with Ca++ and Ca++ activated ATPase dependence, e) conoid penetration, f) induction of a parasitophorous vacuole, a protective and exchange site, interiorization of the parasite. The invasion is an active, oriented and specific process depending on chemical factors as energy sources, cations, as well as microviscosity and membrane structures. Toxoplasma gondii stimulates T cell subsets and induces lymphokine (IFN gamma, IL2) release.