Influenza neuraminidase is an enzyme that plays a role in the spread of the influenza virus through the body. The enzyme acts to break bonds with the host cell to allow a virus to circulate through the body rather than becoming stuck. This facilitates the movement of influenza through the airways and into other regions of the patient's body to create widespread infection. One class of antiviral drugs known as neuraminidase inhibitors work to combat influenza by binding to this enzyme so it cannot work.
The influenza virus is famous for its mutation ability; each flu season, it is slightly different, and this makes it very difficult to combat. One of the things that changes is the structure of the neuraminidase on the surface of each virus. Another complex, hemagglutinin, is also involved in the virulence of the virus. Influenza is classified by the type of hemagglutinin and neuraminidase found on its surface with designations like H2N5 or H1N1 for a particularly infamous strain.
The hemagglutinin on the surface of the virus helps it bind to a cell so it can infect it, while the influenza neuraminidase will cleave the bond when the virus is ready to move on. Together, the paired complexes allow the virus to infect and spread, and it can also leap between patients when people cough without covering their mouths or share utensils. The structure of the influenza neuraminidase can vary, and can determine which species the virus infects.
As influenza viruses replicate, they mutate. Changes in the structure of influenza neuraminidase may result in a dud virus or in a new strain that can jump species or become particularly aggressive. The changes that favor the virus tend to persist, as those viruses go on to replicate and spread their genetic legacy elsewhere. Flu researchers study the mutations of the virus to learn more about how it spreads and changes over time and to develop appropriate treatments.
Neuraminidase inhibitors can be given in the early stages of infection to shorten the time the patient spends feeling ill. The medications can also be helpful for patients who have difficulty fighting the virus off on their own because of immune compromise. A doctor may feel they are indicated if a patient meets a specific profile and can prescribe oral or injectable forms. Access to these medications is typically limited to prevent their overuse, as doctors do not want to encourage the virus to develop adaptations it can use to sidestep influenza neuraminidase inhibitors.