Quantitative Physicochemistry Meets Epitope Prediction: A Blueprint for Peptide Vaccine Design against DENV-3 NS5 MTase

Background

DENV NS5 is the most conserved viral protein; its N-terminal Methyltransferase (MTase) is essential for RNA capping and a prime drug target. The MTase domain mediates methylation of the viral RNA cap, ensuring genome stability, efficient translation, and evasion of host innate immune responses.

Purpose

To computationally profile the DENV-3 NS5 Methyltransferase (MTase) domain (aa 1-262) in terms of key physicochemical properties, signal peptide/propeptide cleavage potential, and phosphorylation site distribution. To map and prioritize cross-validated linear B-cell epitopes on MTase as candidates to support structure-informed antiviral targeting and peptide-based vaccine/diagnostic development.

Materials and Methods

We analyzed the Methyltransferase (MTase) domain of DENV-3 NS5 (amino acids 1-262) using physicochemical property analysis, SignalP software for predicting signal peptide or propeptide cleavage, NetPhos for potential phosphorylation site mapping, and multiple tools for linear B-cell epitope prediction, including the Emini surface accessibility scale, BepiPred 2.0, and the Kolaskar-Tongaonkar method.

Results

The MT domain (theoretical pI ~9.4) shows alternating charged/flexible segments with near-average predicted solubility and no detectable signal peptide or propeptide cleavage site. High-confidence phosphorylation hotspots cluster at ~3-45, 90-110, and 150-190 and extend toward the C-terminus. Cross-validated linear epitopes concentrate at ~10-59, 148-170, and 185-204/226-259.

Conclusion

The DENV-3 NS5 MTase lacks secretory signals. It exhibits discrete phosphorylation and epitope clusters, yielding peptide candidates for diagnostic and vaccine applications. The study also defines conserved, accessible surfaces for structure-based inhibitor design. This workflow can be generalized to other flaviviral MTases.