Design and In Silico Validation of a Novel Multi-Epitopes Subunit Vaccine Candidate against Lassa Virus Using Reverse Vaccinology Approach

Lassa fever, caused by the Lassa virus (LASV), remains a significant public health threat in West Africa, characterised by annual outbreaks, substantial morbidity, and high case-fatality rates in hospitalized patients. The natural immune response to LASV is often marked by a delayed and weak neutralising antibody response, with survival correlating more strongly with robust cell-mediated immunity (CMI). This immunological profile, combined with the challenges of traditional vaccine development for a Biosafety Level 4 (BSL-4) pathogen, necessitates innovative strategies. This study employed a reverse vaccinology and immunoinformatics approach to design a multi-epitope subunit vaccine against LASV. The viral L segment proteins of LASV obtained from NCBI (NC_004297) were computationally screened for potent and conserved B-cell, cytotoxic T-lymphocyte (MHC-I), and helper T-lymphocyte (MHC-II) epitopes. The most promising epitopes were selected based on antigenicity, immunogenicity, non-allergenicity, and lack of homology to the human proteome. These were assembled into a single chimeric protein construct, which was then subjected to comprehensive in silico characterization, including analysis of its physicochemical properties, structural integrity, and safety profile. The potential immunogenicity was evaluated through computational immune simulation. A 24.38 kDa multi-epitope vaccine construct was designed, comprising highly antigenic B-cell and T-cell epitopes linked with appropriate spacers. Physicochemical analysis predicted the construct to be hydrophilic, highly antigenic, and non-allergenic, with a moderate potential for soluble expression in Escherichia coli . Immune simulations predicted that the vaccine could elicit a strong and balanced immune response, characterized by robust activation and proliferation of both CD4 + and CD8 + T-cell populations, induction of immunological memory, and a cytokine profile skewed towards a protective Th1 response (IFN-γ). Functional enrichment analysis carried out suggested that the vaccine construct possesses intrinsic immunomodulatory properties, with strong associations to gene expression regulation and nucleic acid binding. The computationally designed and validated multi-epitope construct represents a promising vaccine candidate against Lassa virus. Its design is rationally tailored to induce the CMI response critical for LASV clearance. This in silico study provides a strong foundation for subsequent pre-clinical development, including protein expression and in vivo immunogenicity and efficacy testing in appropriate animal models.