title: Comparison of allele frequencies of Plasmodium falciparum merozoite antigens in malaria infections sampled in different years in a Kenyan population.
abstract: Plasmodium falciparum merozoite antigens elicit antibody responses in malaria-endemic populations, some of which are clinically protective, which is one of the reasons why merozoite antigens are the focus of malaria vaccine development efforts. Polymorphisms in several merozoite antigen-encoding genes are thought to arise as a result of selection by the human immune system.
  
  
  
  The allele frequency distribution of 15 merozoite antigens over a two-year period, 2007 and 2008, was examined in parasites obtained from children with uncomplicated malaria. In the same population, allele frequency changes pre- and post-anti-malarial treatment were also examined. Any gene which showed a significant shift in allele frequencies was also assessed longitudinally in asymptomatic and complicated malaria infections.
  
  
  
  Fluctuating allele frequencies were identified in codons 147 and 148 of reticulocyte-binding homologue (Rh) 5, with a shift from HD to YH haplotypes over the two-year period in uncomplicated malaria infections. However, in both the asymptomatic and complicated malaria infections YH was the dominant and stable haplotype over the two-year and ten-year periods, respectively. A logistic regression analysis of all three malaria infection populations between 2007 and 2009 revealed, that the chance of being infected with the HD haplotype decreased with time from 2007 to 2009 and increased in the uncomplicated and asymptomatic infections.
  
  
  
  Rh5 codons 147 and 148 showed heterogeneity at both an individual and population level and may be under some degree of immune selection.
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya. liochola@kemri-wellcome.org.
authors.forename: Lynette Isabella
authors.initials: LI
authors.lastname: Ochola-Oyier
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: John
authors.initials: J
authors.lastname: Okombo
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: Njoroge
authors.initials: N
authors.lastname: Wagatua
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: Jacob
authors.initials: J
authors.lastname: Ochieng
authors.affiliation: Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Tetteh
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: Greg
authors.initials: G
authors.lastname: Fegan
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: Philip
authors.initials: P
authors.lastname: Bejon
authors.affiliation: KEMRI-Wellcome Trust Collaborative Programme, P.O. Box 230, Kilifi, 80108, Kenya.
authors.forename: Kevin
authors.initials: K
authors.lastname: Marsh
mesh_terms: D000953:Antigens, Protozoan / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007630:Kenya; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D052940:Merozoites; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000953:Antigens, Protozoan; D008565:Membrane Proteins
keywords: Malaria; Merozoite; Plasmodium; Rh5