AMA1 is a type I integral membrane protein. It is produced by mature P. falciparum schizonts in infected erythrocytes AMA1 has become a leading candidate vaccine antigen. This is based on several facts, most notably that in several field studies an association was found between antibodies to the ectodomain of AMA1 and protection against clinical malaria. Also, in the Gambia, presence of antibodies to AMA1 and MSP-1 has been shown to enhance clearance of chloroquine resistant parasites in vivo.