DNA Nanostructure-Templated Multivalency Enables Broad-Spectrum Virus Inhibition.

The rapid evolution and antigenic diversity of influenza A viruses (IAVs) continue to challenge antiviral strategies, highlighting the need for broadly effective and modular therapeutic platforms. While single-domain nanobodies and DNA aptamer-based inhibitors have emerged as promising candidates, their efficacy is limited by monomeric binding to the hemagglutinin (HA) proteins populating the viral envelope. A programmable antiviral platform based on a honeycomb-shaped designer DNA nanostructure (HC-DDN) engineered to multivalently display HA-targeting ligands with nanometer precision is presented. Two constructs are synthesized, HC-Nanobody and HC-Aptamer, organized in trimeric clusters to match the native HA trimer geometry. Using murine-adapted H1N1 and H3N2 models, it is shown that both constructs outperform their free counterparts in viral neutralization and cytoprotection. HC-Nanobody construct achieves >99% inhibition of viral entry and improves cell viability by 35-45% at nanomolar concentrations. To assess translational relevance, the HC-Nanobody construct in a porcine IAV infection model is further evaluated, where it maintains high antiviral efficacy (>97% inhibition) and confers a 30-55% increase in cell viability relative to free nanobodies, confirming robust cross-species performance. Overall, this work demonstrates the power of geometry-matched multivalency to enhance viral neutralization and provides a rational blueprint for designing broad-spectrum antivirals against rapidly evolving respiratory pathogens.