title: Stable patterns of allelic diversity at the Merozoite surface protein-1 locus of Plasmodium falciparum in clinical isolates from southern Vietnam.
abstract: The extent of allelic diversity at the Merozoite Surface Protein-1 locus of Plasmodium falciparum (PfMSP-1) was examined in isolates collected from symptomatic patients living in a mesoendemic area in southern Vietnam. The variable blocks 2, 4 and 10 were typed by polymerase chain reaction and 24 PfMSP-1 gene types were defined as unique combinations of allelic types detected in each variable block. Nineteen PfMSP-1 gene types were identified and 182 parasite populations were fully typed among 102 isolates. Forty-eight (47%) patients harbored more than one typed parasite population, and one patient had at least eight genetically distinct subpopulations. As previously shown in the same endemic area, recombination between blocks 4 and 10 was significantly less frequent than expected from random assortment of allelic types. The distribution of PfMSP-1 gene types, however, did not differ significantly from that observed in isolates collected in the same area 17-24 mo before the present study. Furthermore, the prevalence of the most common gene types and the average number of different gene types harbored by the same host did not decrease with age. This argues against the prominence of frequency-dependent immune selection of PfMSP-1 polymorphisms in this parasite population.
authors.affiliation: Department of Medical Zoology, Nagoya University School of Medicine, Japan. muferrei@usp.br
authors.forename: M U
authors.initials: MU
authors.lastname: Ferreira
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Zhou
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: O
authors.initials: O
authors.lastname: Kaneko
authors.forename: H
authors.initials: H
authors.lastname: Van Thien
authors.forename: S
authors.initials: S
authors.lastname: Isomura
authors.forename: K
authors.initials: K
authors.lastname: Tanabe
authors.forename: F
authors.initials: F
authors.lastname: Kawamoto
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000483:Alleles; D000818:Animals; D002648:Child; D005787:Gene Frequency; D014644:Genetic Variation; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology*; D020066:Merozoite Surface Protein 1; D008875:Middle Aged; D017720:Molecular Epidemiology; D010963:Plasmodium falciparum / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000145:classification / Q000235:genetics*; D015800:Protozoan Proteins / Q000145:classification / Q000235:genetics*; D014744:Vietnam / Q000453:epidemiology
chemical_list: D020066:Merozoite Surface Protein 1; D011498:Protein Precursors; D015800:Protozoan Proteins