DNA Nanostructure‐Templated Multivalency Enables Broad‐Spectrum Virus Inhibition

Abstract 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.