Comparison of allele frequencies of Plasmodium falciparum merozoite antigens in malaria infections sampled in different years in a Kenyan population.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSION
Rh5 codons 147 and 148 showed heterogeneity at both an individual and population level and may be under some degree of immune selection.
['Ochola-Oyier|Lynette Isabella|LI|', 'Okombo|John|J|', 'Wagatua|Njoroge|N|', 'Ochieng|Jacob|J|', 'Tetteh|Kevin K|KK|', 'Fegan|Greg|G|', 'Bejon|Philip|P|', 'Marsh|Kevin|K|']
D000953:Antigens, Protozoan 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 D008297:Male D008565:Membrane Proteins D052940:Merozoites D010963:Plasmodium falciparum D011110:Polymorphism, Genetic D017422:Sequence Analysis, DNA
Plasmodium Merozoite Malaria Rh5