Overview of Toxoplasma host cell interactions. (A). Innate immune responses are initiated by Toll-like receptor (TLR) and CCR5 recognition of Toxoplasma-derived factors. (B). Parasite invasion is accomplished by the release of micronemal adhesins that interact with host surface factors. This is then followed by rhoptry secretion that results in the formation of the moving junction and in the release of parasite factors (e.g ROP2 family members, ROP16, ROP18, and PP2c-hn) that either interact with the parasitophorous vacuole (PV) (ROP2 family and ROP18) or are transported to the host cytoplasm (ROP16) or nucleus [PP2c-hn (177)]. Some of these factors (ROP16 and ROP18) are polymorphic virulence factors. (C). Intracellular parasites reorganize host mitochondria and endoplasmic reticulum as well as the host microtubule organizing center and cytoskeleton around the PV. Host microtubules associated with LDL-loaded cholesterol form membrane tubules that push into the PV and are wrapped with the dense granule protein GRA7. (D). Small soluble nutrients freely diffuse across the PV and then are taken up by the parasite presumably by membrane transporters. (E). Host transcription is regulated either by the parasite directly activating host transcription factors or by the parasite triggering host signaling cascades that culminate in activating the host transcription factors. Changes in host gene expression can act to either promote parasite growth, immune evasion, virulence, or bradyzoite development.