Designing a Novel 3D Scaffold for Multiepitope Vaccine Development: Engineering Ag85a Protein for Enhanced Stability and Antigenicity

Designing multi epitope vaccine (MEV) by reverse vaccinology has become immensely important in the area of vaccine research due to the emergence of new pathogens as well as rise of multi drug resistant old evils like tuberculosis. Administering a vaccine may have the best possibility to save mankind from these unforeseeable events. The strategy of designing a MEV in-silico lies in a few basic steps, including procuring the amino acid sequence of the B cell and T cell epitopes from literature search, bioinformatics approach to construct a potent immunogen capable of eliciting both humoral and cell mediated response. But the challenge lies in the construction of a stable protein with a compact tertiary structure. Merely joining the epitopes one after another, may not be sufficient to achieve this. In this study, a methodology has been detailed to tackle this great challenge using a simple approach of protein engineering. A scaffold based MEV has been designed for the very first time against Mtb by converting a vaccine candidate protein, Ag85A into a scaffold by truncating its non-immunogenic regions so the gaps could be filled by the highly immunogenic epitopes. The stability of the MEV was estimated by molecular dynamics simulation.