Detection of the Rhoptry Neck Protein Complex in <i>Plasmodium</i> Sporozoites and Its Contribution to Sporozoite Invasion of Salivary Glands
Mamoru Nozaki, Minami Baba, Mayumi Tachibana, Naohito Tokunaga, Motomi Torii, Tomoko Ishino
Abstract
Sporozoites are the motile infectious stage that mediates malaria parasite transmission from mosquitoes to the mammalian host. This study addresses the question whether the rhoptry neck protein complex forms and functions in sporozoites, in addition to its role in merozoites. By applying coimmunoprecipitation and sporozoite stage-specific gene knockdown assays, it was demonstrated that RON2, RON4, and RON5 form a complex and are involved in sporozoite invasion of salivary glands via their attachment ability. These findings shed light on the conserved invasion mechanisms among apicomplexan infective stages. In addition, the sporozoite stage-specific gene knockdown system has revealed for the first time in Plasmodium that the RON2 and RON4 interaction reciprocally affects their stability and trafficking to rhoptries. Our study raises the possibility that the RON complex functions during sporozoite maturation as well as migration toward and invasion of target cells.