Hemagglutinin and Neuraminidase (HA/NA)

Hemagglutinin (HA) and Neuraminidase (NA) are the two primary glycoproteins found on the surface of the influenza virus and are critical for the viral life cycle [1]. Hemagglutinin is a lectin that mediates viral entry by binding to sialic acid receptors on the host cell surface and subsequently facilitating the fusion of the viral envelope with the host cell membrane [2]. Neuraminidase is an enzyme that functions as a sialidase, cleaving terminal sialic acid residues to allow newly formed virions to detach from the host cell and spread to uninfected cells [3]. These proteins are the primary targets for seasonal influenza vaccines, which typically aim to induce antibodies against the HA protein to neutralize the virus [4]. Antiviral drugs such as oseltamivir, zanamivir, and peramivir act as neuraminidase inhibitors, effectively trapping the virus on the cell surface and limiting the spread of infection [5]. Additionally, some antiviral agents like umifenovir target the hemagglutinin-mediated fusion process to prevent viral entry [6]. Understanding the structure and function of HA and NA is essential for monitoring viral evolution and developing effective countermeasures against seasonal and pandemic influenza [1].

Other names

Influenza surface glycoproteinsHANAH and NSialidaseHemagglutinin-neuraminidase

Neuraminidase inhibitors (e.g., oseltamivir) block the enzymatic cleavage of sialic acid to prevent viral release from host cells, while hemagglutinin inhibitors (e.g., umifenovir) prevent viral attachment or membrane fusion to block entry.