Computational design of a multi-epitope mRNA vaccine against orthopoxviruses: A path toward comprehensive poxvirus protection.

Along with the recent outbreak of monkeypox (MPOX), there are worries about other outbreaks of the poxvirus genus that threaten global public health. Until now, although there are no specific vaccines for MPOXV, there are no comprehensive vaccines for all dangerous poxviruses. This research utilizes immunoinformatics and structural vaccinology methodologies to develop a multi-epitope mRNA vaccine targeting variola virus (VARV), vaccinia virus (VACV), monkeypox virus (MPOXV), and cowpox virus (CPXV), which are four pathogenic orthopoxviruses (OPV). Accordingly, A29L, M1R, A35R, B6R, and F8L antigens were selected. Then, their sequences were retrieved and aligned to determine the conserved parts of each antigenic region among these four types of viruses. Different immunoinformatic methods were employed for forecasting B-cell, cytotoxic T lymphocytes (CTL), and helper T lymphocytes (HTL) epitopes. The epitopes were analyzed through a filtering process that checked for antigenicity, toxicity, allergenicity, and cytokine inducibility. The goal was to find epitopes that can make both T- and B-cells react. The vaccine was constructed and modeled via the trRosetta server. Molecular docking was employed between the epitopes and adjuvant receptors along with MHC type I and II molecules. Subsequently, the best structure with low energy was selected, and molecular dynamics (MD) simulations were performed. The immunological simulation data indicated that the developed vaccine possesses significant potential to provoke both cellular and humoral immune responses. Finally, with in vitro and in vivo experiments in the future, the designed vaccine could be a promising candidate for vaccination against pathogenic poxviruses.