Influenza virus hemagglutinin (HA) and neuraminidase (NA) glycoproteins (HA/NA)

The influenza virus hemagglutinin (HA) and neuraminidase (NA) are the two major glycoproteins found on the surface of the influenza A and B viral envelopes [1]. Hemagglutinin is a lectin that mediates the binding of the virus to sialic acid-containing receptors on the surface of host cells, followed by the fusion of the viral and endosomal membranes to release the viral genome [2]. Neuraminidase is an enzyme that cleaves terminal sialic acid residues from glycoproteins and glycolipids, a process essential for the release of progeny virions from infected cells and for preventing viral aggregation [3]. These proteins are the primary targets of the host's neutralizing antibody response and are the key components of seasonal influenza vaccines [4]. Therapeutically, neuraminidase is the target of widely used antiviral drugs like oseltamivir and zanamivir, which prevent the spread of the virus within the respiratory tract [5]. Hemagglutinin is also a target for antiviral development, with drugs like umifenovir acting to inhibit the fusion process [6]. Because these proteins undergo frequent antigenic drift and occasional antigenic shift, they are subject to constant monitoring for the emergence of drug-resistant strains and for vaccine strain selection [1][3]. Citations: [1] UniProt Consortium. "Influenza virus surface glycoproteins." UniProtKB. [2] Skehel, J. J., & Wiley, D. C. (2000). "Receptor binding and membrane fusion in virus entry: the influenza hemagglutinin." Annual Review of Biochemistry. [3] Gamblin, S. J., & Skehel, J. J. (2010). "Influenza hemagglutinin and neuraminidase membrane glycoproteins." Journal of Biological Chemistry. [4] Krammer, F. (2019). "The human antibody response to influenza A virus infection and vaccination." Nature Reviews Immunology. [5] StatPearls Publishing. "Neuraminidase Inhibitors." (2023). [6] Blaising, J., et al. (2014). "Arbidol as a broad-spectrum antiviral: an update." Antiviral Research.

Other names

HemagglutininNeuraminidaseSialidaseHANASurface glycoproteins

Neuraminidase inhibitors (e.g., oseltamivir) competitively inhibit the viral neuraminidase enzyme, preventing the cleavage of sialic acid and thus trapping progeny virions at the host cell surface. Hemagglutinin inhibitors (e.g., umifenovir) prevent viral entry by blocking the conformational changes required for membrane fusion or by interfering with receptor binding.