A genome-wide computational approach for therapeutic targets identification and synthetic peptide assembly enable rational vaccine design against Arcanobacterium haemolyticum

Arcanobacterium haemolyticum is a Gram-positive bacterium responsible for pharyngitis as well as skin and soft tissue infections. While pharyngitis caused by A. haemolyticum is generally treatable with antibiotics, severe systemic infections require accurate differentiation from other pharyngitis-causing pathogens, as misdiagnosis can lead to serious or even fatal outcomes. Currently, there are no standardized treatment protocols for A. haemolyticum -associated systemic infections, highlighting the importance of precise diagnosis to ensure effective therapy. Furthermore, the growing resistance to commonly used antibiotics represents a major public health concern, and untreated infections caused by this bacterium may become increasingly problematic. Therefore, this study aimed to identify novel therapeutic targets and to design a multi-epitope subunit vaccine against A. haemolyticum using subtractive proteomics and reverse vaccinology approaches. An antigenic protein was selected to predict potential B- and T-cell epitopes, which were subsequently evaluated for their immunogenic properties. Based on these epitopes, four vaccine constructs incorporating suitable adjuvants and linkers were designed. Among them, construct V1 exhibited superior stability, as confirmed by immunological and physicochemical analyses, molecular docking with the host receptor, normal mode analysis, and extensive MD simulations, including RMSF, RMSD, Rg, SASA, hydrogen bond analysis, MM-PBSA binding free energy calculations, PCA, and DCCM. Moreover, the immune simulation demonstrated that the construct might produce a strong immune response, and in silico cloning predicted its suitability for a bacterial expression system. Overall, this computational study identified promising and a stable vaccine candidate, underscoring the potential of in silico approaches in accelerating vaccine and drug development against A. haemolyticum infections.