ASPECTS OF IMMUNITY FOR THE AMA-1 FAMILY OF MOLECULES IN HUMANS AND NONHUMAN-PRIMATES MALARIAS

The apical membrane antigen (AMA-1)family of malaria merozoite protein s is characterised by a high degree of inter-species conservation Evid ence that the protein (PK66/AMA-1) from the simian parasite Plasmodium knowlesi was protective in rhesus monkeys suggested that the 83kDa P. falciparum equivalent (PF83/AMA-1) should be investigated for protect ive effects in humans. Here we briefly review pertinent comparative da ta, and describe the use of an eukaryotic full length recombinant PF83 /AMA-1 molecule to develop a sensitive ELISA for the determination of serological responses in endemic populations. The assay has revealed s urprisingly high levels of humoral response to this quantitatively min or antigen. We also show that PK66/AMA-1 inhibitory mAb's are active a gainst merozoites subsequent to release from schizont-infected red cel ls, further implicating AMA-I molecules in red cell invasion.