Circumsporozoite Protein (None)

Circumsporozoite protein (CSP) is the major surface protein of the sporozoite stage of malaria parasites belonging to the genus *Plasmodium*. It is a secreted, glycosylphosphatidylinositol (GPI)-anchored protein that forms a dense coat on the parasite's surface and plays essential roles in parasite development, motility, and host cell invasion. CSP is the antigenic target of leading malaria vaccines such as RTS,S. It facilitates migration from oocysts in mosquito midguts to salivary glands and subsequently enables binding and invasion of hepatocytes (liver cells) in mammals. Proteolytic cleavage regulates exposure/switching between adhesive/nonadhesive conformations required for successful transition between migratory states within hosts versus invasive states during liver entry.

Antibodies against CSP block sporozoite invasion of hepatocytes.