The unique life cycle of Plasmodium vivax leads to asymptomatic infections and clinical relapses. It poses significant challenges for malaria surveillance and global eradication efforts. Serology has emerged as a promising surveillance technology. In our previous work, we identified a panel of eight P. vivax antigen markers that demonstrated high sensitivity and specificity in detecting recent exposure (hypnozoite carriers) in P. vivax endemic cohorts. However, the translational potential of these serological tools has been limited by inherent protein characteristics, such as low specificity and structural instability.
To overcome these limitations, this study focuses on B cell epitopes, the specific antigen regions for antibody binding, which may provide improved performance over the antigen markers.
Using computational immunology tools, we predicted both conformational and linear B cell epitopes with potentially high antigenicity in nine proteins [Pvs16, MSP5, MSP1-19, RBP2b(P87), MSP8, PvCSS, Pv-fam-a(PVX_096995), EBP, PTEX150]. Subsequently, epitope screening experiments identified the best-performing epitope peptides that have superior seroprevalence in IgG responses to sera from endemic regions, including the Solomon Islands, Papua New Guinea, and Brazil. Compared to recombinant protein markers, the combined use of multiple epitopes achieved higher sensitivity and specificity. Validation using longitudinal cohort samples from Brazil (n=426) further confirmed that some epitopes effectively distinguished recent infections from past infections (AUC>0.7). Additionally, a random forest-based surveillance model demonstrated that a combination of best-performing antigens plus epitopes further improved classification accuracy (AUC=0.896).
These findings strongly support the potential of P. vivax serological surveillance technologies, contributing valuable insights toward global malaria eradication efforts.