title: Structural and antigenic polymorphism of the 35- to 48-kilodalton merozoite surface antigen (MSA-2) of the malaria parasite Plasmodium falciparum.
abstract: Merozoite surface antigen MSA-2 of the human parasite Plasmodium falciparum is being considered for the development of a malaria vaccine. The antigen is polymorphic, and specific monoclonal antibodies differentiate five serological variants of MSA-2 among 25 parasite isolates. The variants are grouped into two major serogroups, A and B. Genes encoding two different variants from serogroup A have been sequenced, and their DNA together with deduced amino acid sequences were compared with sequences encoded by other alleles. The comparison shows that the serological classification reflects differences in DNA sequences and deduced primary structure of MSA-2 variants and serogroups. Thus, the overall homologies of DNA and amino acid sequences are over 95% among variants in the same serogroup. In contrast, similarities between the group A variants and a group B variant are only 70 and 64% for DNA and amino acid sequences, respectively. We propose that the MSA-2 protein is encoded by two highly divergent groups of alleles, with limited additional polymorphism displayed within each group.
authors.affiliation: Centre for Parasite Biology, University of Edinburgh, Scotland, United Kingdom.
authors.forename: B
authors.initials: B
authors.lastname: Fenton
authors.forename: J T
authors.initials: JT
authors.lastname: Clark
authors.forename: C M
authors.initials: CM
authors.lastname: Khan
authors.forename: J V
authors.initials: JV
authors.lastname: Robinson
authors.forename: D
authors.initials: D
authors.lastname: Walliker
authors.forename: R
authors.initials: R
authors.lastname: Ridley
authors.forename: J G
authors.initials: JG
authors.lastname: Scaife
authors.forename: J S
authors.initials: JS
authors.lastname: McBride
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics*; D001483:Base Sequence; D002872:Chromosome Deletion; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015345:Oligonucleotide Probes; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics* / Q000276:immunology; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000954:Antigens, Surface; C064417:GYMSSA antigen, Plasmodium falciparum; D008562:Membrane Glycoproteins; D015345:Oligonucleotide Probes; D015800:Protozoan Proteins