Immunopharmacological design of a multi-epitope vaccine targeting sarbecovirus Spike glycoprotein

Sarbecoviruses pose a continued pharmacological and immunological challenge due to their zoonotic potential and high genetic variability, demanding broadly protective vaccine strategies with conserved viral antigens. This study aimed to design a broad-spectrum multi-epitope vaccine predicted to neutralize potential future spillovers of Horseshoe bat sarbecoviruses, a likely evolutionary forebear. Using a reverse vaccinology pipeline, priority was given to high-affinity CTL, HTL, and B-cell epitopes from the Spike glycoprotein that had conserved antigenicity throughout the Sarbecovirus subgenus. A multi-epitope vaccine strategy was employed to enhance broad immunogenicity against conserved sarbecovirus regions. Being stable, soluble, and non-allergenic, the final chimeric construct showed a good physicochemical profile. Analysis of population coverage revealed that the chosen epitopes might technically stimulate an immunological reaction in almost 96.89% of the global population, hence reducing HLA-restriction bias. Structural modeling utilizing AlphaFold 3 exposed a native-like fold, which was confirmed by molecular docking with the human ACE2 receptor. The high binding affinity (energy score - 1484.7 kcal/mol) and unique interfacial interactions imply the vaccine can successfully emulate the viral pathogen, hence stopping viral entry. Later in silico immune simulations forecast a powerful Th1-polarized response distinguished by high IFN-gamma concentrations and the fast development of immunological memory. At last, virtual cloning into the pET-28a( +) vector and codon optimization verified the possibility of high-yield expression in E. coli. Further experimental validation is required to confirm its immunogenicity and protective efficacy.