title: Allelic variation in the circumsporozoite protein of Plasmodium falciparum from Thai field isolates.
abstract: Allelic variation in the Plasmodium falciparum circumsporozoite (CS) protein gene has been examined by sequencing the entire gene in 15 isolates from an endemic area of Thailand. The isolates contain a total of six new allelic forms of the tetrapeptide repeats and eight variants of the T cell epitope (TCE) region of the CS gene. All nucleotide substitutions in the TCE are nonsynonymous. There is no apparent association between the sequence patterns in the repeats and in the TCE. Comparison of the TCE with published sequences has shown that most variants of our isolates are not identical to those found in different geographic areas, suggesting geographic variation in genetic diversity of the CS protein. In a phylogenetic tree, the new Thai alleles did not cluster together, suggesting a considerable heterogeneity within some geographic areas. Furthermore, analyses of tetrapeptide repeats from a number of isolates and strains showed evidence of three genetic mechanisms for the generation of variation in the repeats of the CS gene: point mutation, duplication of one or more repeat units, and intragenic recombination.
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Jongwutiwes
authors.forename: K
authors.initials: K
authors.lastname: Tanabe
authors.forename: M K
authors.initials: MK
authors.lastname: Hughes
authors.forename: H
authors.initials: H
authors.lastname: Kanbara
authors.forename: A L
authors.initials: AL
authors.lastname: Hughes
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000737:chemistry; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000235:genetics* / Q000276:immunology; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D000953:Antigens, Protozoan; D017931:DNA Primers; D016054:DNA, Protozoan; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan