We have identified and functionally characterized a novel Plasmodium falciparum surface-related antigen ( Pf SRA) as a potential multistage vaccine candidate. The antigen is localized on both merozoites and gametocytes with high anti- Pf SRA growth inhibition assay activity in laboratory strains and clinical isolates. Abstract Plasmodium falciparum erythrocyte invasion is a multistep process that involves a spectrum of interactions that are not well characterized. We have characterized a 113-kDa immunogenic protein, PF3D7_1431400 (PF14_0293), that possesses coiled-coil structures. The protein is localized on the surfaces of both merozoites and gametocytes, hence the name Plasmodium falciparum surface-related antigen ( Pf SRA). The processed 32-kDa fragment of Pf SRA binds normal human erythrocytes with different sensitivities to enzyme treatments. Temporal imaging from initial attachment to internalization of viable merozoites revealed that a fragment of Pf SRA, along with Pf MSP1 19, is internalized after invasion. Moreover, parasite growth inhibition assays showed that Pf SRA P1 antibodies potently inhibited erythrocyte invasion of both sialic acid–dependent and –independent parasite strains. Also, immunoepidemiological studies show that malaria-infected populations have naturally acquired antibodies against Pf SRA. Overall, the results demonstrate that Pf SRA has the structural and functional characteristics of a very promising target for vaccine development.
【저자키워드】 naturally acquired immunity, Plasmodium falciparum, novel antigens, Malaria vaccine, erythrocyte invasion,