Comparative structural analysis of Nipah virus V proteins highlights V-MDA5 complex stability in pig and bat isolates

Nipah virus (NiV) V protein antagonizes host interferon (IFN) signaling by targeting melanoma-differentiation association protein 5 (MDA5). This study investigated structural features of NiV V proteins from pig (iP-V) and bat (iB-V) isolates and their interactions with MDA5 using protein crystallization and computational modeling. Recombinant proteins were expressed in Escherichia coli and purified by affinity chromatography. Crystallization screening produced initial hits for iP-V; however, diffraction-quality crystals were not obtained, likely due to the intrinsically disordered N-terminal region that limits structural resolution. Homology modeling and molecular docking revealed that both proteins engage the MDA5 superfamily 2 helicase domain (MDA_SF2) (amino acids 534-836) and are predicted to disrupt β-sheet architecture critical for ATPase function. The C-terminal domain (CTD) contains zinc finger domains (ZnFDs) essential for MDA5 interaction. iP-V retains eight conserved amino acids required for coordination of two zinc ions, whereas iB-V carries substitutions predicted to partially affect one ZnFD based on structural modeling, without abolishing MDA5 antagonism. Both proteins show comparable predicted binding affinities to MDA5, although structural analyses indicate subtle differences in interaction networks. These findings suggest that minor variations within the CTD may modulate interaction profiles rather than binding strength, while preserving immune evasion capacity, providing a basis for future experimental validation.