Genetic Diversity of the Plasmodium falciparum Glutamate-Rich Protein R2 Region Before and Twelve Years after Introduction of Artemisinin Combination Therapies among Febrile Children in Nigeria.

Abstract

The genetic diversity of glutamate-rich protein (GLURP) R2 region in Plasmodium falciparum isolates collected before and 12 years after the introduction of artemisinin combination treatment of malaria in Osogbo, Osun State, Nigeria, was compared in this study. Blood samples were collected on filter paper in 2004 and 2015 from febrile children from ages 1-12 years. The R2 region of the GLURP gene was genotyped using nested polymerase chain reaction and by nucleotide sequencing. In all, 12 GLURP alleles were observed in a total of 199 samples collected in the two study years. The multiplicity of infection (MOI) marginally increased over the two study years; however, the differences were statistically insignificant (2004 samples MOI = 1.23 versus 2015 samples MOI = 1.47). Some alleles were stable in their prevalence, whereas two GLURP alleles, VIII and XI, showed considerable variability between both years. This variability was replicated when GLURP sequences from other regions were compared with ours. The expected heterozygosity (He) values (He = 0.87) were identical for the two groups. High variability in the rearrangement of the amino acid repeat units in the R2 region were observed, with the amino acid repeat sequence DKNEKGQHEIVEVEEILPE more prevalent in both years, compared with the two other repeat sequences observed in the study. The parasite population characterized in this study displayed extensive genetic diversity. The detailed genetic profile of the GLURP R2 region has the potential to help guide further epidemiological studies aimed toward the rational design of novel chemotherapies that are antagonistic toward malaria.