NEURAMINDASE (also known as Sialidase) is an enzyme that hydrolyzes terminal sialic acid residues on poly-saccharide chains. It is predominantly expressed in microorganisms such as bacteria and viruses. Cleavage of sialic acid residues by neuraminidase is believed to play several roles in infection by influenza viruses. It is thought to assist in the penetration of mucosal linings, the invasion of target cells, the elution of progeny viruses from infected cells, and the prevention of self-aggregation. Thus, neuraminidase is an important target for influenza drug development and simple, direct and automation-ready procedures for measuring neuraminidase activity find wide applications in research and drug discovery. This neuraminidase assay measures the sialic acid released by neuraminidase in one step. The change in color intensity of the reaction product at 570nm or fluorescence intensity at lambda ex/em = 530/585nm is directly proportional to neuraminidase activity in the sample.