Structural analysis of antigenic variation and adaptive evolution of the H5N1 neuraminidase gene
Muyiwa S. Adegbaju, Oluwabuyikunmi Owo-Odusi, Eden T. Wirtz, Olanrewaju B. Morenikeji, Olusola Ojurongbe, Bolaji N. Thomas
Abstract
The concern regarding H5N1 outbreak, particularly the accelerated mutagenesis of its core genomic elements, underscores the persistent threat of influenza to global health. Neuraminidase (NA), a pivotal sialidase integral to virion egress and propagation, comprises nine distinct isoforms, exhibiting unique evolutionary trajectories and structural adaptations. Despite extensive characterization of hemagglutinin subtypes, the functional divergence of the nine NA subtypes remains inadequately understood.
Introduction
Highly pathogenic avian influenza A (HPAI) H5N1 viruses continue to pose a significant threat to global health due to their high virulence and persistent pandemic potential [1]. Effective surveillance and a deep understanding of viral adaptation are crucial for mitigating the risk of animal-to-human or human-to-human transmission and severe disease. A key determinant of influenza virus pathogenicity and a primary target for host immune responses and antiviral interventions is the surface glycoprotein neuraminidase (NA) [2,3]. NA facilitates viral release from infected cells and is considered a promising vaccine target, although its inherent variability complicates vaccine development [4–6].
Materials and Methods
Structural alignment and comparative analysis of neuraminidase subtypes
To prepare a comprehensive dataset for family-specific position identification, nine high-resolution neuraminidase crystal structures were initially superimposed using the MatchMaker algorithm in ChimeraX for precise core structural alignment [50]. Visualizations were generated via Chimera and annotated with CorelDRAW X24.
Results
Structural analysis
The neuraminidase protein typically functions as a homotetramer, with its catalytic domain (spanning residues 83–468) possessing a well-resolved crystal structure crucial for enzyme activity. This domain was the focus of our structural analysis. We examined the structural relationships among the nine avian influenza A virus (IAV) NA subtypes by selecting a single monomeric chain (Chain A) of NA1 (PDB: 2HTY [24]) as the reference structure for superimposition.
Discussion
Integrating sequence and structural information remains paramount for a comprehensive understanding of the molecular mechanisms underlying biological specificity within protein families. While sequence analysis provides insights into conservation and divergence at the residue level, protein structure elucidates the spatial arrangement of key functional elements, revealing conserved interaction interfaces, binding pockets, and allosteric sites that may not be apparent from sequence alignments alone [30,31].
Conclusion
The persistent and multifaceted threat of H5N1 adaptation necessitates a paradigm shift from reactive containment to proactive risk mitigation. This reorientation hinges on leveraging the genetic diversity in dead-end hosts as a crucial leading indicator of pandemic potential, thereby fundamentally transforming global surveillance efforts. Our molecular understanding of the K207 dynamic switch presents a high-value therapeutic target, while phylogenetic data underscores the urgent need for its rapid development and deployment.
Acknowledgments
This work is a part of the collaboration between Systems Immunology and Computational Biology Research group, Rochester Institute of Technology and the Center for Emerging and Re-emerging Infectious Diseases, Ladoke Akintola University of Technology, Ogbomosho, Nigeria.
Citation: Adegbaju MS, Owo-Odusi O, Wirtz ET, Morenikeji OB, Ojurongbe O, Thomas BN (2026) Structural analysis of antigenic variation and adaptive evolution of the H5N1 neuraminidase gene. PLoS Comput Biol 22(1): e1013903. https://doi.org/10.1371/journal.pcbi.1013903
Editor: Dina Schneidman, Hebrew University of Jerusalem, ISRAEL
Received: August 13, 2025; Accepted: January 9, 2026; Published: January 16, 2026
Copyright: © 2026 Adegbaju et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the paper, its Supporting information files, are on Zenodo at https://doi.org/10.5281/zenodo.16814769.
Funding: This research was supported by a USDA-NIFA research grant 2023-67016-39917 (BNT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The Authors have declared that no competing interests exists.]
