Immunoinformatics-driven construction of a next-generation epitope-based vaccine from conserved hypothetical proteins of M. tuberculosis for enhanced TB control.

Mycobacterium tuberculosis (Mtb) has afflicted humanity for centuries. BCG is the only vaccine available for TB, but it shows limited protective efficacy in adults. Therefore, there is an urgent need to develop universal vaccines for controlling TB worldwide. In this study, four conserved mycobacterial hypothetical proteins (HPs) were analyzed for their immunological, structural, and functional properties using various computational tools. The IFN-γ-inducing MHC class I and II binding peptides of the four conserved HP antigens were predicted by the IFNepitope 2.0 server. After detailed in silico validations, the most immunogenic, non-toxic, non-allergenic B-cell, CTL and HTL epitopes with broad population coverage and conservancy were selected for developing a new epitope-based vaccine (IDE) construct. Furthermore, the final vaccine construct was verified for its antigenicity, toxicity, allergenicity and solubility properties. Molecular docking and MD simulations analyses showed conformational stability and high binding affinity of the designed vaccine with TLR4, MHC-I, and MHC-II immune receptors. In silico immune simulation revealed the production of high levels of IgG, T-helper, T-cytotoxic cells, IFN-γ and interleukins against the final vaccine construct. Thus, the IDE vaccine could be a potent next-generation epitope-based vaccine candidate to stimulate both humoral and cellular responses against Mtb. However, further animal studies are needed to validate the immunogenicity and biological efficacy of the proposed vaccine construct.