Targeting G and F proteins of human metapneumovirus: An in silico strategy for multiepitope vaccine design

Human metapneumovirus (hMPV) is a predominant etiological agent of acute respiratory infections in infants, the elderly, and immunocompromised individuals; however, no approved vaccinations are available. To fulfill this unmet requirement, we developed an innovative multi-epitope subunit vaccine aimed at conserved domains of hMPV's glycoprotein (G) and fusion protein (F) utilizing immunoinformatics methodologies. Utilizing reverse vaccinology, 79 immunogenic epitopes (31 MHC-I, 48 MHC-II) were discovered, associated with optimal spacers, and then fused to cholera toxin B adjuvant to augment immunogenicity. The resulting construct of 528 amino acids (57.5 kDa) exhibited superior physicochemical characteristics, including good stability (instability index: 36.8), solubility (GRAVY: -0.63), and non-allergenicity. Structural validation indicated a revised tertiary model with 95.7% of residues in preferred Ramachandran regions. Molecular docking demonstrated significant binding score to the innate immune receptors TLR3 and TLR4, whereas immunological simulations forecasted substantial long-term protection via increased IgM/IgG titers, memory B & T-cell proliferation, and generation of IFN-γ/IL-2. The candidate attained 94.7% global population coverage and was codon-optimized for elevated expression in Escherichia coli (CAI: 0.95; GC: 68.9%), with effective in silico cloning. This study introduces a computationally verified, structurally stable hMPV vaccine with extensive protective capabilities, showcasing immunoinformatics as a strategic framework for expediting development against new respiratory infections. Additional in vitro and in vivo investigations are necessary to validate efficacy.