Dynamic development of parasitophorous vacuole of Eimeria tenella transfected with the yellow fluorescent protein gene fused to different signal sequences from apicomplexan parasites.

Intracellular stages of Eimeria tenella reside within a membrane-bound parasitophorous vacuole (PV). PVs of apicomplexan parasites like E. tenella play important roles in nutrient acquisition, multiplication, and evasion of host immune responses. Different signal sequences from apicomplexan parasites were investigated in the transfected E. tenella for their functions in targeting yellow fluorescent protein (YFP) to subcompartments and the dynamic development of the PV of E. tenella was studied. Two 5' terminal signal sequences derived from Toxoplasma gondii GRA8 protein and Plasmodium falciparum repetitive interspersed family protein, respectively, were confirmed to target YFP to the PVs of the transfected E. tenella, suggesting that signal sequences are functionally conserved among Apicomplexa. Three structurally different types of PVs were observed during the endogenous development of the transfected E. tenella in vitro. In addition, three subcompartments in the PV, namely, membranous extensions into the host cell cytosol, membranous extensions into the vacuolar lumen, and particle-like bodies, were detected during schizogony of the parasite.