Establishment of reference reagents for single-radial-immunodiffusion assay on the 2022/23 seasonal influenza vaccine in Japan and their quality validation

Abstract

Potency test of influenza vaccine is currently performed using a single-radial-immunodiffusion (SRID) assay, which requires a reference antigen and anti-hemagglutinin (HA) serum as reference reagents. The reagents must be newly prepared each time the strain used for vaccine production is changed. Establishing reference reagents with consistent quality is, therefore, crucial to accurately and precisely conduct vaccine potency tests. Here, we established the reference reagents for the SRID assay to conduct lot release tests of quadrivalent influenza vaccines in Japan for the 2022/23 influenza season. The potency stability during storage of some reference antigens was confirmed. Furthermore, we evaluated the cross-reactivity of each antiserum raised against the HA protein of two lineages of influenza B virus toward the different lineage of influenza B virus antigen to select a suitable procedure of SRID assay for accurate measurement. Finally, the intra-laboratory reproducibility of the SRID assay using the established reference reagents was validated, and then the SRID reagents had sufficiently consistent quality comparable to that of the reagents used for testing vaccines in past influenza seasons. Our study could contribute to the quality control of influenza vaccines.