title: Association between particular polymorphic residues on apical membrane antigen 1 (AMA-1) and platelet levels in patients with vivax malaria.
abstract: Apical membrane antigen 1 (AMA-1) is an immunogenic type 1 integral membrane protein, present in all Plasmodium spp., that probably has a role in the initiation of the invasion process of the erythrocyte. The DNA sequence of variable domain I of the Plasmodium vivax ama1 gene was sequenced in Brazilian isolates obtained from thrombocytopenic patients (n = 32) and patients with normal platelet counts (n = 22). There was a significant negative correlation between parasite density and platelet counts. It was concluded that there is an additional effect of sequence on platelet counts. The presence of amino-acid residues Y(193) and S(210) was associated significantly with normal platelet counts in P. vivax malaria, independent of the level of parasitaemia (p <0.0001). These data have implications for AMA-1-based vaccine design and suggest the possible use of this molecule as a marker of morbidity.
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte (MG), Brazil.
authors.forename: P
authors.initials: P
authors.lastname: Grynberg
authors.forename: C J
authors.initials: CJ
authors.lastname: Fernandes Fontes
authors.forename: E Martins
authors.initials: EM
authors.lastname: Braga
mesh_terms: D000328:Adult; D019943:Amino Acid Substitution; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D016780:Malaria, Vivax / Q000097:blood* / Q000276:immunology* / Q000469:parasitology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology; D008875:Middle Aged; D008969:Molecular Sequence Data; D010966:Plasmodium vivax / Q000302:isolation & purification*; D010976:Platelet Count / Q000379:methods; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000235:genetics* / Q000276:immunology
chemical_list: D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium