neuraminidase

Examples of neuraminidase in the following topics:

• Replicative Cycle of Influenza A

  • Hemagglutinin and neuraminidase molecules cluster into a bulge in the cell membrane.
  • The mature virus buds off from the cell in a sphere of the host phospholipid membrane, acquiring hemagglutinin and neuraminidase with this membrane coat (Step 7).
  • As before, the viruses adhere to the cell through hemagglutinin; the mature viruses detach once their neuraminidase has cleaved sialic acid residues from the host cell.
  • Drugs that inhibit neuraminidase, such as oseltamivir, therefore prevent the release of new infectious viruses and halt viral replication.
  • Contrast the roles of hemagglutinin and neuraminidase throughout the major stages of the replicative cycle of influenza A virus

• Antiviral Agents that Prevent Virus Uncoating or Release

  • Neuraminidase is an enzyme on the capsid of influenza virus .
  • Tamiflu and Relenza are trend names of two drugs used to treat influenza infections by targeting neuraminidase.
  • The image depicts the major components of the virus structure, including the neuraminidase.

• Vaccines and Anti-Viral Drugs for Treatment

  • Tamiflu works by inhibiting an enzyme (viral neuraminidase) that allows new virions to leave their infected cells.
  • (a) Tamiflu inhibits a viral enzyme called neuraminidase (NA) found in the influenza viral envelope.
  • (b) Neuraminidase cleaves the connection between viral hemagglutinin (HA), also found in the viral envelope, and glycoproteins on the host cell surface.
  • Inhibition of neuraminidase prevents the virus from detaching from the host cell, thereby blocking further infection.

• Coryza and Influenza

  • Hemagglutinin (HA) and neuraminidase (NA) are the two large glycoproteins on the outside of the viral particles.
  • The two classes of antiviral drugs used against influenza are neuraminidase inhibitors and M2 protein inhibitors (adamantane derivatives).
  • Neuraminidase inhibitors are currently preferred for flu virus infections since they are less toxic and more effective.

• Emergence of Viral Pathogens

  • For example, if a pig was infected with a human influenza virus and an avian influenza virus at the same time, an antigenic shift could occur, producing a new virus that had most of the genes from the human virus, but a hemagglutinin or neuraminidase from the avian virus.
  • The resulting new virus would likely be able to infect humans and spread from person to person, but it would have surface proteins (hemagglutinin and/or neuraminidase) not previously seen in influenza viruses that infect humans, and therefore most people would have little or no immune protection.

• Current Epidemics

  • Antiviral drugs such as the neuraminidase inhibitor oseltamivir (Tamiflu) have been used to treat influenza; however, their effectiveness is difficult to determine due to much of the data remaining unpublished.