Comparative Structural and Biophysical Profiling of Dengue Virus NS5 Methyltransferase Identifies DENV-4 as a Prioritized Antiviral Target

Background

The NS5 Methyltransferase (MTase) domain is essential for the capping and replication of dengue virus RNA and for the virus's evasion of the host immune response, making it a promising antiviral target.

Purpose

To assess the structural and biophysical characteristics of the NS5 MTase across the four Dengue Virus Serotypes (DENV-1-4) and to identify features relevant to antiviral and antibody design.

Materials and Methods

An in silico comparative study was performed, incorporating sequence mapping, Fab-interface modelling, electrostatic and hydrophobicity profiling, developability prediction using Poly-Specificity Reagent (PSR)-like metrics, and electrostatic-stability prediction across a range of pH and ionic-strength conditions.

Results

The NS5 MTase was highly conserved among serotypes, with a few substitutions at the predicted Fab-binding interfaces. The dominant contact residues were Pro114 (DENV-1/4), Tyr88 (DENV-2) and Ile49 (DENV-3). Surface electrostatic features were largely conserved, with slight hydrophobic variation. Among the developability descriptors examined, DENV-4 separated most clearly from the reference distribution in the PSR-like space, consistent with a favourable predicted non-specificity profile. Maximum electrostatic stability for all serotypes occurred at pH 6.0-8.0 and low ionic strength (≤0.05 M), and the energy landscape within this window was flattest for DENV-4.

Conclusion

Despite the high conservation of the NS5 MTase, serotype-specific structural differences may influence its therapeutic targeting. DENV-4 demonstrated the most favourable predicted stability and developability, marking it as a promising candidate for structure-based antiviral and antibody development.