Integrated Pangenome, Immunoinformatics, and Structural Biology Approaches for the Design of a Multi-Epitope Vaccine Against Streptococcus Anginosus

Background: Streptococcus anginosus is an opportunistic bacterial pathogen associated with clinically significant infections, including brain abscesses, bacteremia, empyema, and infective endocarditis. The absence of an approved vaccine against this organism warrants investigation of potential preventive candidates. Accordingly, this study investigated the computational design and characterization of a multi-epitope vaccine targeting S. anginosus. Methods: Comparative analysis of 28 complete S. anginosus genomes was undertaken to distinguish core genes and identify suitable antigenic protein targets. The shortlisted proteins were examined for B-cell, CTL, and HTL epitopes, followed by the construction of a vaccine sequence containing the selected epitopes and β-defensin-3 as an adjuvant. Further analyses examined epitope conservancy, physicochemical characteristics, three-dimensional conformation, molecular docking with immune receptors, molecular dynamics simulations, and predicted immune responses. Results: Genomic comparison yielded 627 core genes, providing a basis for antigen selection. The resulting vaccine comprised 272 amino acid residues and showed favorable computational predictions for antigenicity, stability, solubility, and allergenicity. Structural assessment indicated acceptable stereochemical characteristics, while conservancy screening revealed complete sequence identity for several epitopes among their corresponding homologous proteins. Docking calculations identified possible contact interfaces with TLR2 and TLR4, with TLR2 receiving the more negative ClusPro score. Molecular dynamics trajectories characterized conformational variations within the vaccine–receptor complexes. The selected epitopes yielded an estimated worldwide population coverage of 99.23%. Immune-response modeling additionally predicted antibody-associated and cellular immune activity. Conclusions: The proposed vaccine displayed computational characteristics that support its further investigation as a preventive candidate against S. anginosus. Experimental studies are necessary to determine its safety, immunogenicity, and protective efficacy.