An Alternative Approach to Design a Vaccine Based on Epitope-Rich Domain Regions Against Enterococcus faecium

Abstract

Due to its resistance to routinely used antibiotics, Enterococcus faecium has become the fourth most frequently identified nosocomial infection, posing a severe hazard to human health. Although vaccination as an alternative control method has garnered a lot of interest, presently no vaccination contrary to this bacterium that has been approved in clinical trials. This mandates the formulation of a ground-breaking immunisation strategy. The purpose of this work was to create an epitope-rich domain-based vaccine against E. faecium infections using the pathogen's Secreted Antigen A (SagA) and Protein P54, both of which are potential vaccine candidates. From both protein antigens, a total of two domains were selected as highly antigenic and IFN-inducing. Both HLA-A*02:01 and HLA-DRB1*01:01 alleles interacted with the identified domains. Vaxecium is an epitope-rich domain-based vaccination made up of domains of both SagA and P54 antigens that were fused together by linkers and adjuvant. Using several bioinformatics methods, the 3D structure of the epitoperich domain-based vaccination construct was predicted, improved, and verified. Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) demonstrated a significant binding relationship and stability with the epitope-rich domain-based vaccination design (TLR4). Before being cloned into the pET-28a (+) vector, Vaxecium was codon-optimized for expression in the E. coli K12 system. This research lays the groundwork for developing an antibiotic-resistant E. faecium vaccine that is both safe and effective.