Neuraminidase is an enzyme found on the surface of certain viruses, including the influenza virus. It plays a crucial role in the virus's ability to spread within the host by cleaving sialic acid residues on the surface of host cells. This action helps the virus release newly formed viral particles, allowing them to infect other cells. In addition to its role in viral replication, neuraminidase is a target for antiviral medications, such as oseltamivir (commonly known as Tamiflu). These medications inhibit the enzyme's activity, reducing the severity and duration of influenza infections.