Flu virus surface protein and drug. Molecular model of the neuraminidase glycoprotein enzyme found on the surface of the influenza (flu) virus, in complex with the drug oseltamivir. The presence of neuraminidase on the virus surface enables the virus to be released from the host cell. Oseltamivir (marketed as Tamiflu) binds to neuraminidase, inhibiting it and so preventing the virus from being able to infect other cells. It can be taken to prevent infection, or to reduce the symptoms and the duration of the infection.