The sorozoite, the merozoite, and the infected red cell: Parasite ligands and host receptors

In this review, we discuss what is known about the receptors and ligands involved in both salivary gland and hepatocyte invasion by sporozoites. In addition, we will discuss what is known of the role of motility in target cell invasion, since sporozoite invasion of host cells is a dynamic process that is more than just the sum of parasite ligands and host cell receptors. Many lines of evidence suggest that target cell invasion by Apicomplexan parasites is not a passive process in which the parasite induces its internalization by the host cell but instead is an active process rcquiring the actin cytoskeleton of the parasite. An understanding of parasite motility and the way in which interactions between sporozoite ligands and host cell receptors are involved in the movement of the parasite into the cell will therefore lead to a better understanding of host cell invasion.