Novel antibody-independent receptor-binding SPR-based assay for rapid measurement of influenza vaccine potency

A WHO workshop organized following the 2009 H1N1 pandemic recommended development of alternative influenza vaccine potency assays as high priority that could expedite the release of vaccine lots in the face of future influenza pandemics. We have developed an antibody independent, simple, high throughput receptor-binding SPR-based potency assay, which does not require any reference antisera and could be used for rapid HA quantitation and vaccine release in pandemic scenarios. The assay utilizes synthetic glycans with sialic acid (SA) of either α-2,6 or α-2,3 linkage to galactose. Only functionally active forms of HA (trimers and oligomers) recognize the SA-glycans and are quantified in this receptor-binding SPR assay. The SA-glycan SPR assay demonstrated broad dynamic range for quantitation of HA content in influenza vaccines from different manufacturers for both seasonal (A/H1N1, A/H3N2, B lineages) and pandemic influenza (A/H5N1, A/H7N9) strains with high reproducibility and low variability across multiple assays. In addition, the SA-glycan SPR assay is indicative of active HA stability, and can accurately quantify HA content in alum and oil-in-water adjuvanted influenza vaccines. Importantly, there was a good agreement between HA content determined by the SPR-based potency assay and the traditional SRID assay.