Genetic Diversity and Allelic Frequency of Glutamate-Rich Protein (GLURP) inPlasmodium falciparumIsolates from Sub-Saharan Africa

Abstract

Glutamate-rich protein is a Plasmodium falciparum (Pf) antigen found in all stages of the parasite and has been reported to induce clinical immunity. The R0 and R2 regions have been found to exhibit a high degree of conservation, therefore serving as a good vaccine design material. We assayed the genetic diversity of Pf glurp genes in the R0 and R2 regions, as well as evaluated the role of seasonality on allelic frequency. A total of 402 genomic DNA samples, extracted from filter paper blood samples, were screened by nested polymerase chain reaction (PCR) analysis of Pf glurp R0 and R2 regions, in addition to fragment analysis of the polymorphic regions to identify allelic diversity of the parasite population. We found an extensive heterogeneity in the R2 region in general, and this heterogeneity is seasonally dependent, indicative of region plasticity. The R0 region displayed genetic conservation, as expected. We conclude that positive genotyping results with glurp R0 region should be seen as indicative of an active Pf infection, requiring adequate treatment. In addition, we advocate extending the possibility that an R0 region genotypic positivity could serve as diagnostic tool, thereby reducing cases of untreated or poorly treated infection, contributory to recrudescence or treatment failure.

Plasmodium falciparum genotype and gametocyte prevalence in children with uncomplicated malaria in coastal Ghana

“…Geometric mean MOIs for msp1 and msp2 of 1.90 and 1.88 were slightly lower than obtained in an earlier report from the middle belt of Ghana where MOI was 2.3 in July/August, [52] but similar to another report of MOI in southern Ghana which was 1.93 [24] and 1.3 in 2013 [53]. This discrepancy may be due to differences in ecological zones [54], malaria transmission intensity [36, 55] and/or the treatment-seeking behaviour of malaria patients within the various population [56, 57]. …”

Critical Evaluation of Molecular Monitoring in Malaria Drug Efficacy Trials and Pitfalls of Length-Polymorphic Markers

“…The adoption of capillary electrophoresis (CE)-based sizing of PCR products largely resolved limitations of gel-based sizing protocols, such as insufficient resolution of minimal size differences, particularly among fragments larger than 500 bp, or unequal loading of variable PCR yields leading to apparent but artificial size differences. These limitations are particularly relevant for glurp genotyping, since amplicons of the glurp R2 region often surpass 1,000 bp in size, and CE-based glurp genotyping was not routinely used in most laboratories (8, 9). …”

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

“…33 However, the GLURP gene displays some antigenic diversity, with differing allelic variants, depending on geography and transmission intensity. 34 A previous report originating from our study area has revealed extensive genetic diversity in the MSP2 gene. 35 To expand our understanding of rsu3 rsu1 rsu2 rsu1 6 (46) 5 (46) rsu3 rsu2 rsu2 rsu1 2 (15) 1 (9) rsu3 rsu2 rsu3 rsu1 1 (8) 0 (0) rsu3 rsu2 rsu2 rsu3 2 (15) 0 (0) rsu3 rsu2 rsu1 rsu2 1 (8) 1 (9) rsu3 rsu1 rsu3 rsu1 1 (8) 0 (0) rsu3 rsu2 rsu2 rsu2 0 (0) 3 (27) rsu3 rsu1 rsu1 rsu1 0 (0) 1 (9) the genetic structure of P. falciparum and delineate potential contribution of ACT to malaria transmission intensity, we analyzed the parasite's GLURP R2 diversity in field isolates collected 12 years since artemisinin-combination therapy was introduced for the treatment of clinical malaria in Nigeria.…”

“…39 The observation of a considerable number of different GLURP genotypes in our study demonstrates its extensive diversity, with our finding being in agreement with previous studies which correlated genetic diversity with disease transmission intensity. 34,40,41 Malaria parasites use their extensive genetic diversity to their advantage as variability confers the ability to evade human immune responses, compromising vaccine efficacy and that of antimalarial drugs.…”