In silico designing of a novel multiple epitope vaccine against vancomycin resistant Enterococcus faecalis; An...

Vancomycin-resistant Enterococcus faecalis continues to pose a major therapeutic challenge, especially as resistance genes such as the rare VanE gene continue to rise globally. With the escalation of antimicrobial resistance and no available commercial vaccines, alternative preventive strategies are necessary. This research designed a novel multi-epitope vaccine candidate against Vancomycin Resistant E. faecalis using immunoinformatics tools. The predicted T and B-cell epitopes underwent screening for allergenicity, antigenicity, and toxicity using immunoinformatics-based tools, with major focus on T-cell epitopes. Successful epitopes were combined with an appropriate adjuvant (L7/L12 ribosomal protein) and linkers (EAAAK, AAY, GPGPG) to create a multi-epitope vaccine. Our designed vaccine indicated desirable antigenicity with Vaxigen score of 0.6132, non-allergenic characteristics, solubility score of 0.583, along with high theoratical population coverage. The secondary and tertiary structures of the protein were modelled using tools, including PsiPred and trRosetta, respectively, and the tertiary structure was refined using the GalaxyRefine server. The ERRAT score was 92.4303 and 93.9% of residues were within desirable regions of the ramachandran plot confirmed the credibility and quality of the final construct. The docking studies showed promising poses and weighted scores with TLR-2 receptor. The vaccine construct was cloned using the PET28a vector via SnapGene for the purpose of expression studies in E. coli. The overall vaccine construct also activated both cell-mediated and humoral immunity when subjected to C-ImmSim. These in-silico analyses were foundational for endorsing a potential vaccine that can induce immune responses and complement control of multi-drug-resistant E. faecalis and warrant further examination in experimental models.