Population genomics of <i>Plasmodium ovale</i> species in sub-Saharan Africa

Abstract

<i>Plasmodium ovale curtisi</i> (<i>Poc)</i> and <i>Plasmodium ovale wallikeri</i> (<i>Pow</i>) are relapsing malaria parasites endemic to Africa and Asia that were previously thought to represent a single species. Amid increasing detection of ovale malaria in sub-Saharan Africa, we performed a population genomic study of both species across the continent. We conducted whole-genome sequencing of 25 isolates from Central and East Africa and analyzed them alongside 20 previously published African genomes. Isolates were predominantly monoclonal (43/45), with their genetic similarity aligning with geography. <i>Pow</i> showed lower average nucleotide diversity (1.8×10^-4) across the genome compared to <i>Poc</i> (3.0×10^-4) (p < 0.0001). Signatures of selective sweeps involving the dihydrofolate reductase gene were found in both species, as were signs of balancing selection at the merozoite surface protein 1 gene. Differences in the nucleotide diversity of <i>Poc</i> and <i>Pow</i> may reflect unique demographic history, even as similar selective forces facilitate their resilience to malaria control interventions.