Immunopharmacological and structural design of a polyprotein based multi epitope vaccine against Powassan virus

Powassan virus (POWV) poses a growing neurotropic threat with limited immunopharmacological interventions, requiring the development of targeted vaccine strategies. The current study focuses on developing a specific vaccine using bioinformatics tools to target T- and B-cell epitopes from a genome polyprotein sequence of POWV. Four vaccine constructs with possible immunogenic qualities were assembled. Two specific epitopes were selected from B-cell, and T-cell for each construct. The heat-labile enterotoxin S63 adjuvant was attached to the N-terminal, while the PADRE order and the His-tag were added to the C-terminal with appropriate linkers. The vaccine constructs showed 62%, 80%, 90%, and 72% of average global population coverage. The Ramachandran scores were observed to be ≥ 90%, and the instability index was 35.13, validating stable structures. Docking analysis showed strong affinity for V1-TLR7 (-1380), V2-TLR7 (-1615.7), V2-TLR8 (-1033.8), V3-TLR7 (-1692.7), V3-TLR8 (-1097.6), ACE (-1127.2), V4-TLR7 (-1689.4), and V4-TLR10 (-1240.8 kcal/mol) complexes, respectively. However, molecular dynamics simulations revealed a consistent interaction pattern for the complex TLR8-construct3. The vaccine constructs ligated into the pBR322 vector showed successful insertion and expression. A strong immune response was observed, with elevated IgM + IgG concentrations within 10 days of injection, which normalized by 30-35 days. In conclusion, the current research highlights the possibility of an innovative vaccine against the virus. To extend our efforts and bridge the gap between vaccine design and reducing the burden of POWV, further in vitro and in in vivo studies are necessary.