In Silico Design and Evaluation of a Multi-Epitope Vaccine Candidate Against Staphylococcus haemolyticus

S. haemolyticus is an emerging multidrug-resistant pathogen that frequently causes nosocomial infections, yet no licensed vaccine is currently available for its prevention. In this study, conserved surface-associated proteins were screened to identify B-cell, cytotoxic T-lymphocyte, and helper T-lymphocyte epitopes for the design of a multi-epitope vaccine candidate. The selected epitopes were assembled into a 254-amino acid construct containing human β-defensin-3, the PADRE sequence, and selected linkers. The resulting construct was predicted to be antigenic, non-allergenic, and non-toxic, with favorable physicochemical properties, structural stability, and solubility. The selected CTL and HTL epitopes provided an estimated global population coverage of 97.5%, indicating broad predicted coverage across different populations. Structural analysis supported the quality of the refined three-dimensional model. Molecular docking predicted favorable interactions between the vaccine construct and TLR2 and TLR4, while 200 ns molecular dynamics simulations indicated that receptor-vaccine interactions were maintained during the simulation period. Codon optimization and in silico cloning further supported the feasibility of recombinant expression in Escherichia coli. Overall, the computational analyses support the proposed multi-epitope construct as a potential vaccine candidate against S. haemolyticus and provide a basis for its further experimental evaluation.