Plasmodium sporozoite antigens

Plasmodium sporozoite antigens are a group of proteins expressed on the surface of the malaria parasite during the sporozoite stage, which is the infectious form injected into the human host by Anopheles mosquitoes (UniProt, 2024). The most prominent member of this group is the Circumsporozoite Protein (CSP), which covers the entire surface of the sporozoite and is essential for parasite development, motility, and the invasion of host hepatocytes (PubMed: 33053386). Other significant antigens include the Thrombospondin-related anonymous protein (TRAP) and Cell-traversal protein for ookinetes and sporozoites (CelTOS), which facilitate the parasite's movement through skin tissue and entry into the liver (Nature Communications, 2020). These antigens serve as the primary targets for pre-erythrocytic vaccines, such as RTS,S/AS01 (Mosquirix) and R21/Matrix-M, which aim to elicit neutralizing antibodies and T-cell responses to prevent the establishment of a liver-stage infection (WHO, 2023). By blocking the parasite at this initial stage, these therapies can prevent both the clinical symptoms of malaria and the subsequent transmission back to mosquitoes. However, the high degree of genetic polymorphism in these antigens across different Plasmodium strains presents a major challenge for achieving universal and long-lasting vaccine efficacy (The Lancet, 2023).

Other names

Circumsporozoite protein (CSP)Thrombospondin-related anonymous protein (TRAP)Cell-traversal protein for ookinetes and sporozoites (CelTOS)Sporozoite surface protein 2 (SSP2)Sporozoite microneme protein essential for cell traversal (SPECT)P52/P36 antigens

Neutralization of sporozoite infectivity and inhibition of liver stage entry