title: A study of genetic diversity in the gene encoding the circumsporozoite protein (CSP) of Plasmodium falciparum from different transmission areas--XVI. Asembo Bay Cohort Project.
abstract: We have investigated the genetic diversity of the gene encoding the CS protein. A total of 75 complete and 96 partial sequences are studied. We find high levels of genetic polymorphisms as evidenced by 50 and 24 alleles at the Th2R and Th3R epitopes, respectively. Overall, we find that African isolates are more polymorphic as compared with parasites from other geographic regions. We conclude that the uneven geographic polymorphism may have an adverse impact on the effectiveness of vaccines based on this antigen alone. We find extensive polymorphism in the repeat allotypes, or RATs. In order to explore how the protein structure may impose restrictions in the number of repeats, we have simulated the stability of the structure of the tandem repeat region. Our analysis suggests that the protein structure may play an important role in the observed polymorphism in the number of CS repeats in Plasmodium falciparum. We explored the linkage and recombination events among the polymorphic sites. We found that putative recombination events overlap with linked sites. We discuss how this pattern is explained by the action of positive natural selection, where the recombination events detected are convergent mutations. We conclude that it is inappropriate to use linkage-recombination patterns on genes under positive selection for assessing the structure of parasite populations.
authors.affiliation: Department of Biology, Emory University, Atlanta, GA, USA. aescalante@cdc.gov
authors.forename: Ananias A
authors.initials: AA
authors.lastname: Escalante
authors.forename: Heather M
authors.initials: HM
authors.lastname: Grebert
authors.forename: Raul
authors.initials: R
authors.lastname: Isea
authors.forename: Ira F
authors.initials: IF
authors.lastname: Goldman
authors.forename: Leonardo
authors.initials: L
authors.lastname: Basco
authors.forename: Magda
authors.initials: M
authors.lastname: Magris
authors.forename: Sukla
authors.initials: S
authors.lastname: Biswas
authors.forename: Simon
authors.initials: S
authors.lastname: Kariuki
authors.forename: Altaf A
authors.initials: AA
authors.lastname: Lal
mesh_terms: D000483:Alleles; D000818:Animals; D001483:Base Sequence; D015331:Cohort Studies; D018984:Epitopes, T-Lymphocyte / Q000032:analysis / Q000145:classification; D019143:Evolution, Molecular; D005787:Gene Frequency; D017125:Genes, Protozoan; D005843:Geography; D016778:Malaria, Falciparum / Q000473:pathology / Q000635:transmission*; D008562:Membrane Glycoproteins / Q000235:genetics; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics*; D012641:Selection, Genetic
chemical_list: D018984:Epitopes, T-Lymphocyte; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan