Designing a multi-epitope vaccine targeting UPF0721 of meningitis-causing Salmonella enterica serovar Typhimurium strain L-4126 by utilizing immuno-informatics and in silico approaches

Salmonellae, which pose a significant global health threat, cause a range of infections, including gastroenteritis and, in severe cases, meningitis, particularly in immunocompromised individuals. The emergence of multi-drug-resistant Salmonella enterica serovar Typhimurium underscores the urgent need for effective vaccine development. In this study, a chimeric vaccine was constructed, targeting UPF0721 transmembrane proteins of serovar Typhimurium strain L-4126, which are critical for its life cycle. Fifteen highly antigenic epitopes, including CTL, HTL, and B-cell epitopes, were recognised and assessed for their ability to elicit T-cell and IFN-γ-mediated immune-responses. Physiochemical analyses confirmed their safety profiles. The vaccine construct integrated these epitopes with linkers (EAAAK, GPGPG, AAY, and KK) and β-defensin adjuvants to enhance immunogenicity, stability, and molecular interactions. Molecular docking demonstrated robust binding affinity, particularly with TLR8, and highlighted the vaccine's structural stability and immunogenic potential. The eigenvalue analysis (9.728895) validated the vaccine's flexibility and favorable biophysical properties. Molecular dynamics simulations validated the energy minimization, molecular stability and flexibility assessments. Immune simulation results indicated strong immune responses, while the physicochemical analysis confirmed solubility and stability during recombinant peptide expression in E. coli. This study also explored mRNA vaccine constructs, emphasizing their potential in combating serovar Typhimurium infections such as meningitis. The vaccine construct showed high potential, demanding further investigation into their immune efficacy against serovar Typhimurium infections through experimental assays and medical trials.