An in silico VAR2CSA-based multi-epitope vaccine candidate (PM-MEV-k1) shows favourable Structural and Immune Simulation parameters for protection against placental malaria

Background Placental malaria remains a major cause of maternal anaemia, low birth weight, and infant mortality across sub-Saharan Africa, yet no licensed vaccine currently exists. VAR2CSA mediates parasite sequestration in the placenta, but candidates PRIMVAC and PAMVAC show limited immunogenicity, prompting computational reverse-vaccinology approaches to design improved, broadly protective multi-epitope vaccine candidates. Materials and Methods The VAR2CSA protein sequence was retrieved from UniProtKB and a reverse vaccinology pipeline was employed to assess its conservation, subcellular localisation, and signal/transmembrane features across Plasmodium species. Additionally, immunoinformatics tools were used to predict CTL, HTL, and B-cell epitopes, which were filtered for antigenicity, allergenicity, and toxicity before fusion via EAAAK, AAY, GPGPG, and KK linkers with a built-in TLR4 adjuvant. Physicochemical properties, secondary and tertiary structure modelling, docking, normal-mode analyses s, immune response simulations and codon optimisation for restriction cloning were subsequently evaluated. Results We computationally designed PM-MEV-k1, a 552-residue chimeric construct built from conserved, antigenic VAR2CSA-derived CTL, HTL and B-cell epitopes fused to a built-in TLR4 adjuvant. The candidate scored 0.7323 for antigenicity, predicted to be non-allergenic and non-toxic, and had favourable physicochemical stability and overall hydrophilicity (GRAVY − 0.667). Structural validation revealed 94.6% Ramachandran favourability, strong ProSA and ERRAT quality scores, and a thermodynamically stable TLR4-docking interaction (-50.03 kcal/mol). Immune simulation predicted robust IgG class-switching, sustained CD4+/CD8 + T-cell activation and balanced Th1/Th2 cytokine responses across a standard three-dose immunisation schedule. Successful codon optimisation and in silico restriction cloning confirmed expression readiness in Escherichia coli K-12, supporting downstream experimental development plans. Conclusion: PM-MEV-k1 is projected as a rationally engineered, structurally validated, immunologically promising multi-epitope vaccine candidate with the potential to address key limitations of PRIMVAC and PAMVAC, warranting prioritised recombinant expression, animal immunisation, and clinical trials toward an effective placental malaria vaccine.