Identification of conserved cross-species B-cell linear epitopes in human malaria: a subtractive proteomics and immuno-informatics approach targeting merozoite stage proteins

Abstract

Human malaria, caused byfive Plasmodium species (P. falciparum, P. vivax, P.malariae, P. ovale,andP. knowlesi), remains a significant global health burden.While most interventions targetP. falciparum, the species associated with highmortality rates and severe clinical symptoms, non-falciparum species exhibitdifferent transmission dynamics, remain hugely neglected, and pose a significantchallenge to malaria elimination efforts. Recent studies have reported the presenceof antigens associated with cross-protective immunity, which can potentiallydisrupt the transmission of various Plasmodium species. With the sequencing ofthe Plasmodium genome and the development of immunoinformatic tools, in thisstudy, we sought to exploit the evolutionary history of Plasmodium species toidentify conserved cross-species B-cell linear epitopes in merozoite proteins. Weretrieved Plasmodium proteomes associated with human malaria and applied asubtractive proteomics approach focusing on merozoite stage proteins. Bepipred2.0 and Epidope were used to predict B-cell linear epitopes usingP. falciparumasthe reference species. The predictions were further compared against human andnon-falciparum databases and their antigenicity, toxicity, and allergenicityassessed. Subsequently, epitope conservation was carried out using locallysequencedP. falciparumisolates from a malaria-endemic region in westernKenya (n=27) and Kenyan isolates from MalariaGEN version 6 (n=131). Finally,physiochemical characteristics and tertiary structure of the B-cell linear epitopeswere determined. The analysis revealed eight epitopes that showed high similarity(70-100%) between falciparum and non-falciparum species. These epitopes werehighly conserved when assessed across local isolates and those from theMalariaGEN database and showed desirable physiochemical properties. Ourresults show the presence of conserved cross-species B-cell linear epitopes thatcould aid in targeting multiple Plasmodium species. Nevertheless, validating theirefficacyin-vitroandin-vivoexperimentally is essential