A neuraminidase potency assay for quantitative assessment of neuraminidase in influenza vaccines

VaxArray Influenza Seasonal Neuraminidase Potency Assay (VXI-sNA). a Illustration of a VXI-sNA microarray slide containing 16 identical microarrays in 16 wells. b Schematic of the VXI-sNA array layout of subtype-specific antibodies to N1, N2 subtypes and B-NA. Two different monoclonal antibodies (mAbs) are printed for each subtype and distinguished from one another using (i) or (ii) labeling. The array contains nine replicate spots (~200？μm in diameter) of each monoclonal antibody. c Immunoassay schematic. d Qualitative assessment of VXI-sNA capture mAbs for detection of a panel of recent vaccine strains produced across multiple production platforms with a blue box and checkmark to indicate mAb detection of the listed antigen. Detection was defined as 3× the background intensity. e Signal intensities for each VXI-sNA capture mAb against a panel of historical FluZone vaccines from 2004 to 2012. White/empty boxes indicate signal intensity below the 3× background intensity cutoff, yellow indicates signal intensity between 3× and 20× background intensity, green indicates between 20×–40× background, and blue indicates between 40× and fluorescence saturatio