Cell-traversal protein for ookinetes and sporozoites (CelTOS)

Cell-traversal protein for ookinetes and sporozoites (CelTOS) is a conserved, secreted micronemal protein found in apicomplexan parasites, including malaria-causing Plasmodium species. It plays a critical role in the parasite's ability to traverse host and vector cells during key stages of its lifecycle—specifically, the traversal of mosquito midgut cells by ookinetes and mammalian host cells by sporozoites. CelTOS binds with high specificity to phosphatidic acid on the cytoplasmic face (inner leaflet) of plasma membranes, forming pores that locally disrupt the membrane. This disruption facilitates parasite exit from traversed cells—critical for both transmission through mosquitoes and infection initiation in vertebrate hosts. It has emerged as a promising vaccine candidate due to its immunogenicity and role in parasite infectivity.

Pore formation in host cell membranes, facilitating parasite exit.