Immune Evasion Mechanisms of Plasmodium falciparum in Relation to Clinical Malaria Severity in Enugu State

Plasmodium falciparum employs sophisticated immune evasion strategies including antigenic variation of PfEMP1 surface antigens to escape host immunity, with consequences for clinical disease severity that remain incompletely characterised in Southeast Nigeria. This study investigated the relationship between PfEMP1 domain expression patterns and clinical malaria severity in 240 patients presenting with uncomplicated or severe falciparum malaria at a tertiary hospital in Enugu State, Southeast Nigeria. Peripheral blood samples were collected at presentation, and parasites were cultured for 18 hours. RNA was extracted, and cDNA libraries were profiled for PfEMP1 domain transcript expression using quantitative RT-PCR. Cytokine profiles including TNF-alpha, IL-10, and IFN-gamma were measured by multiplex ELISA. CIDR1-alpha and DBL-beta domain expression were significantly upregulated in severe malaria cases relative to uncomplicated cases (p < 0.001). IL-10 to TNF-alpha ratios were significantly lower in severe cases, suggesting impaired immune regulation. High parasite multiplication rates correlated with dominant expression of rosette-mediating PfEMP1 variants. These findings contribute mechanistic insights into clinical severity determinants in Nigerian falciparum malaria and identify specific PfEMP1 domains as priority targets for future vaccine candidate evaluation. Keywords: PfEMP1, immune evasion, severe malaria, antigenic variation, Enugu State.