Assaying the potency of inactivated viral influenza vaccines is performed using single radial immunodiffusion, which is the globally accepted release method for potency. Under conditions of a rapidly emerging pandemic, such as the 2009 H1N1 influenza pandemic, a recognized obstacle in the delivery of vaccines to the public is the time needed for the distribution of calibrated SRID reagents (antisera and antigen standards) to vaccine manufacturers. Previously, we first described a novel streamlined MS-based assay, CombE-IDMS, which does not rely on antisera/antibodies or reference antigens, as a potential rapidly deployable alternate potency method through a comparison with SRID on adjuvanted seasonal quadrivalent vaccine cell-based (aQIVc) materials. In this report, we further demonstrate that the CombE-IDMS method can also be applied to measure the potency of pre-pandemic H5N1 and H5N8 monovalent vaccine materials, each subtype both unadjuvanted and adjuvanted, through a forced degradation study. Overall, CombE-IDMS results align with those of the gold standard SRID method on both H5N1 and H5N8 materials under conditions of thermal, pH, oxidative and freeze/thaw stress, lending further evidence for the CombE-IDMS method's suitability as an alternate assay for potency of both seasonal and pandemic influenza vaccines.
Keywords: alternate potency; avian influenza; forced degradation; hemagglutinin (HA); isotope dilution mass spectrometry (IDMS).