In-silico identification of b-cell epitopes and derivation of a chimeric protein for development of vaccine against plasmodium falciparum

Abstract

Malaria vaccine development remains a major global health challenge, with Plasmodium falciparum accounting for the majority of malaria-related morbidity and mortality, especially in Sub-Saharan Africa. Despite significant advances in diagnosis and treatment, the efficacy of existing vaccines remains limited due to the parasite's high antigenic variability and epitope diversity. This study aimed to design a novel chimeric vaccine candidate using an in-silico approach, integrating conserved B-cell epitopes from three key P. falciparum antigens: Circumsporozoite Protein (CSP), Apical Membrane Antigen 1 (AMA1), and Merozoite Surface Protein 1 (MSP1). Protein sequences were retrieved from UniProtKB, aligned using MEGA12, and consensus sequences generated. Motif discovery was conducted using the MEME Suite, followed by epitope prediction and analysis via the IEDB Analysis Resource. Selected epitopes were evaluated for antigenicity, surface accessibility, flexibility, hydrophilicity, and beta-turn potential. A chimeric protein was constructed by linking validated B-cell epitopes with GPGPG linkers and an adjuvant sequence (APPHALS) via an EAAAK linker. The final construct was assessed for allergenicity, antigenicity, toxicity, and physicochemical properties using ProtParam, VaxiJen, and AlgPred. The resulting chimeric vaccine candidate was found to be non-allergenic, non-toxic, and highly antigenic (VaxiJen score: 1.1910). It exhibited favorable physicochemical properties, including hydrophilicity (GRAVY: -1.300), thermostability (aliphatic index: 34.51), and suitable half-life for experimental expression. Secondary and tertiary structure predictions confirmed the proper folding and structural stability of the construct. This study demonstrates the potential of computational vaccinology in the rational design of multi-epitope chimeric vaccines. The developed construct provides a promising basis for future experimental validation and could contribute significantly to malaria vaccine development strategies.