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Kimenyi, K. M.

Publications and source records attributed to Kimenyi, K. M..

2 recordsLinked to original sources

Uncovering the genetic diversity of the malaria parasite antigen MSP2 across Sub-Saharan Africa

Genetic diversity in Plasmodium falciparum poses a significant challenge to malaria control and elimination. This is particularly important for developing fully efficacious vaccines, which should include valuable blood stage antigens. Several antigen candidates are highly diverse and require further understanding. We surveyed the genetic diversity of the highly polymorphic merozoite surface protein 2 (MSP2) in 2761 P. falciparum isolates collected across Sub-Saharan Africa. Using PCR-based genotyping and long-read sequencing, we identified extensive diversity among msp2 size variants and sequences. Some size variants were more prevalent than others across different geographical regions, transmission intensities, and time points. These variants comprised multiple unique sequences, of which several were geographically and temporally widespread. Our study reveals greater msp2 sequence diversity than previously known, while also identifying interesting similarities in sequence and gene length across Sub-Saharan Africa. These findings support the further exploration of common msp2 variants in relation to parasite virulence and vaccine development.

microbiology↗

Characterizing Plasmodium falciparum genetic diversity and complexity of infections in clinical malaria infections in Western and Coastal Kenya using the poly-alpha microsatellite marker

BackgroundGenotyping P. falciparum polymorphic merozoite genes to describe parasite genetic diversity and the complexity of malaria infections (COI) is routinely used to assess the effectiveness of malaria control interventions. They are also utilized in anti-malarial drug therapeutic efficacy studies (TES) to differentiate recrudescent parasites from new infections. However, these polymorphic genes are usually under selection. Therefore, neutral microsatellite markers are preferred as they are also easier to genotype. The current study investigated the genetic diversity and COI using the poly- microsatellite marker to provide background information on circulating genotypes before its applied to TES in Kenya. MethodologyDried blood spot (DBS) samples were obtained from 93 participants from a TES in Busia County in 2016 and 92 participants from a malaria monitoring study conducted in Kilifi in 2020. Genotyping of the poly- microsatellite was done by PCR, capillary electrophoresis and the fragment data analyzed using GeneMarker. ResultsAbout 96.7% and 87% of the samples from Busia and Kilifi, respectively, were successfully genotyped. The infections in Busia were mainly polyclonal (80%) with a significantly higher mean COI of 2.9 (p < 0.0001), while those in Kilifi were mostly monoclonal (52.5%) with a mean COI of 1.7. Despite on average a younger population and lower parasite density, both regions had similar expected heterozygosity (He) (Busia = 0.92; Kilifi = 0.90) while Busia recorded a slightly higher number of effective alleles (Ne) (Busia = 10.8; Kilifi = 9.3). ConclusionThe poly- microsatellite genotyping revealed high genetic diversity of malaria parasites in Busia and Kilifi. These findings define the genotypes (fragment sizes) observed in the two Kenyan populations, providing a proof of concept for the utility of poly- in TES studies as a molecular correction tool and for the evaluation of the effectiveness of malaria interventions in Kenya.

genetics↗