Nanometer

One billionth of a meter

Negative-sense RNA

Viral RNA with a base sequence complementary to that of messenger RNA (mRNA). The RNA must be converted to positive-sense RNA by a viral enzyme called RNA polymerase before translation into protein can occur. Viruses that have negative-sense RNA genomes include influenza and Ebola.

Neuraminidase

A protein found on the surface of influenza viruses that is needed for the virus to exit the host cell and infect more cells. The action of this protein is inhibited by the class of antiviral drugs that includes the drug Tamiflu®. In the system using for naming influenza subtypes (H1N1, for example), the N stands for neuraminidase.