Designing a multi-epitope mRNA vaccine to combat human metapneumovirus based on consensus sequence using reverse vaccinology.

Human metapneumovirus (HMPV) ranks among the chief causes of serious respiratory illness in young children, accounting for about 3-10% of hospital admissions for acute lower respiratory tract infections in those under five years of age. Despite recent outbreaks and its rising incidence in recent years, no licensed vaccines or targeted therapies are currently available. In this study, surface viral proteins were selected as antigenic candidates, and their consensus sequences were derived from 782 HMPV genomes. Then using immunoinformatic approaches, immunodominant CTL, HTL, LBL epitopes within these proteins consensus sequence that exhibited high antigenicity, exhibiting no toxicity, no allergenic potential, and broad conservancy across HMPV clades were identified and combined with adjuvants, the PADRE sequence, and linkers for vaccine development. Physicochemical analysis confirmed that the resulting multi-epitope mRNA vaccine is stable under physiological conditions. Molecular docking analyses revealed robust interactions with important immune receptors and subsequent molecular dynamics simulations validated the stability of these complexes over time. Immune simulations predicted robust humoral and cellular responses. Finally, a Kozak sequence was included to enhance mRNA stability and translational efficiency, followed by an MITD sequence to enhance epitope presentation, a TAA codon to terminate translation, and for stability 5' UTR and 3' UTR was added and the engineered mRNA's secondary structure was predicted. Additionally final vaccine construct was cloned in silico into the pVAX1 vector, and virtual agarose gel electrophoresis was performed. These results support the potential of our multi-epitope mRNA vaccine as a promising preventive strategy against HMPV infection.