Molecular basis for reduced neuraminidase inhibitors susceptibility in highly pathogenic avian influenza A (H5N1) viruses: Perspective on refining antiviral strategies and enhancing pandemic preparedness

The increasing resistance cases in influenza A viruses (IAVs) to different classes of antiviral drugs, necessitates for a detailed investigation of molecular interactions governing reduced susceptibility to these drugs. This study explores the molecular basis of the Highly Pathogenic Avian Influenza (HPAI) A H5N1 viruses’ resistance to neuraminidase inhibitors (NAIs), which we identified in our previous study. Using sophisticated protein modeling and docking methods, we investigated two HPAI H5N1 clade 2.2 viruses, A/chicken/India/85459/2008 (N294S) and A/chicken/WestBengal/142121/2008 (E119A + I117V). The N294S substitution provided oseltamivir resistance while retaining zanamivir susceptibility, but the E119A + I117V substitutions resulted in resistance to both zanamivir and oseltamivir. Molecular interactions analyses unveiled that N294S and E119A + I117V substitutions resulted in varying fitness levels, hydrogen bonding, and affinity transitions. It is evident that the impact of different substitutions within the neuraminidase (NA) protein of IAV varies widely depending on the subtype, clade, or the specific NAIs (oseltamivir and zanamivir). Given the variable susceptibility to NAIs caused by distinct substitutions in NA protein, it is critical to implement an integrated surveillance framework that incorporates the One Health approach, involving avian, environmental, mammalian and human’s sources, to monitor susceptibility or resistance profiles of IAVs. This study is the first to investigate the genetic basis for reduced NAIs susceptibility in HPAI H5N1 viruses having dual resistance molecular markers, emphasizing the significance for refining antiviral strategies and improving pandemic preparedness. • Novel insights for reduced susceptibility of Influenza viruses to neuraminidase inhibitors. • Decreased binding affinity and hydrogen bonds interactions govern reduced susceptibility. • Offers optimizing antiviral strategies and pandemic preparedness against Influenza viruses.