Phage-displayed nanobody-peptide conjugates enhance antiviral activity against PRRSV-2 strains

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to pose a major threat to the global swine industry, and effective antiviral neutralization strategies remain limited. Nanobody-peptide conjugates (NPCs) were previously identified as promising antiviral candidates against PRRSV. To enhance the antiviral efficiency, NPCs were displayed on the surface of M13 phage by fusing with coat protein pIII. All phage-NPCs showed strong virus-binding affinity and neutralizing activity against representative PRRSV-2 strains from multiple lineages in vitro, without compromising phage infectivity. Notably, phage-based formats enhanced antiviral activity that persisted for over 60 days at 4 °C. Furthermore, phage-NPCs exerted antiviral effects at both the pre-attachment and post-attachment stages of infection. The stable infectivity under diverse conditions further supports the robustness of this phage-displayed format. Collectively, these findings indicate that phage-displayed NPCs exhibit antiviral function and stability compared with the soluble NPCs, highlighting phage display as a practical approach for PRRSV prevention and control.