Apical membrane antigens lead to evasion of immune system in malaria.

2004 JUN 2 - (NewsRx.com & NewsRx.net) -- Allelic polymorphisms in apical membrane antigen-1 are responsible for evasion of antibody-mediated inhibition in Plasmodium falciparum.

"Apical membrane antigen-1 (AMA-1) is a target of antibodies that inhibit invasion of Plasmodium falciparum into human erythrocytes and is a candidate for inclusion in a malaria vaccine. We have identified a line of P. falciparum (W2mef) less susceptible to anti-AMA1 antibodies raised to the protein from a heterologous parasite line (3D7). We have constructed transgenic P. falciparum expressing heterologous AMA-1 alleles," investigators in Australia report.

"In vitro invasion assays show that these transgenic parasites differ from parental lines in susceptibility to inhibitory antibodies, providing direct evidence that sequence polymorphisms within AMA-1 are responsible for evasion of immune responses that inhibit parasite invasion," said Julie Healer at the Walter & Eliza Hall Institute of Medical Research and colleagues in Australia. "We also generated a parasite line that would express a chimeric AMA-1 protein, in which highly polymorphic residues within domain 1 were exchanged. Inhibition assays suggest that these residues are not sufficient for inhibition by ...