Molecular interactions of cultured turkey kidney cells with specific antigens of Eimeria adenoeides sporozoites.

Earlier studies suggested that specific communication between the parasite and the host cell may play a role in cellular invasion by sporozoites of species of avian Eimeria. In this study, quantification of cellular invasion and modified Western blot analysis were used to explore the possibility that parasite receptors for interaction with the host cell might be involved in the sporozoite-host cell communication. Invasion in cultured cells treated with a homogenate of Eimeria adenoeides sporozoites was approximately 50% lower than that in untreated cultures. When the sporozoite homogenate was solubilized in sodium dodecyl sulfate and electrophoretically separated, components of the cultured host cells bound consistently to sporozoite bands having Mr of 23 and 40 kDa. Biotinylation of intact sporozoites revealed at least 14 biotin-labeled bands, including bands at 23 and 40 kDa, that were considered to be surface molecules. If the sporozoites were incubated in trypsin after they were biotinylated, only two biotinylated bands at 18 and 23 kDa remained; the 40-kDa biotinylated band was not detected. Despite the removal of the majority of the surface molecules, the cell homogenate still bound to the trypsin-treated sporozoites; the intensity of the label was similar to that resulting from the binding of cell homogenate to untreated sporozoites. The data show specific interactions between 23- and 40-kDa sporozoite bands and host cell components, and provide evidence that the 23-kDa molecule may be located on the sporozoite surface and the 40-kDa molecule located intracellularly.