Optimized Expression, Purification, and Rapid Detection of Recombinant Influenza Nucleoproteins Expressed in Sf9 Insect Cells.

Accurate and rapid diagnosis of influenza infection is essential to enable early antiviral treatment and reduce the mortality associated with seasonal and epidemic infections.Immunochromatography is one of the most common methods used for the diagnosis of seasonal human influenza; however, it is less effective for the diagnosis of pandemic influenza virus.Currently, rapid diagnosis kits for pandemic influenza virus rely on the detection of nucleoprotein (NP) or hemagglutinin (HA). NP detection shows higher specificity and is more sensitive than HA detection. In this study, we time-dependently screened expression condition, and report optimal conditions for the expression of recombinant nucleoprotein (rNP), which was 48 h after infection, and the use of the expressed rNP in a rapid influenza diagnosis test (SGT i-flex Influenza A&B Test).We constructed expression vectors that synthesized rNP(antigen) of influenza A and B in insect cells (Sf9 cells), employed the purified rNP to the immunoassay test kit, and clearly distinguished NPs of influenza A and influenza B using the rapid influenza diagnosis kit. This approach may improve the development of rapid test kits for influenza using NP.