Influenza vaccine titer determination using biolayer interferometry (BLI)
© Wheatley et al. 2015
Published: 14 December 2015
Fast, accurate determination of vaccine titer during influenza vaccine manufacture is important in understanding process performance and correctly scaling each process step. Traditionally Single Radial Immunodiffusion (SRID) assays have been used as the 'gold standard' but the assay requires very skilled operators to obtain reproducible results and is relatively low throughput. ELISAs have also been used to determine titer but have lower precision and dynamic range. BLI combines the high throughput characteristics of a 96-well plate based ELISA assay in conjunction with improvements in accuracy and repeatability derived from a simpler direct measurement of mass transfer on binding.
Materials and methods
Samples taken directly from purification steps were assayed with zero sample clean up, having been only diluted with a proprietary ForteBio sample buffer. Protein A and Protein G biosensors were used in the assay. The system uses well plate technology allowing for high sample throughput.
Native samples gave an average result of 53.6 μg/mL. The heat treated samples showed a loss of response to an average value of 7.2 μg/mL, proving they had been inactivated and that the assay is also a test for vaccine potency.
The total analysis time was less than 3 hours on the Octet RED96 System. The BLItz platform allowed at-line sampling to be conducted in the process development laboratories. A change in the vaccine strains or formulation did not require a change in equipment or method: only limited requalification of the assay would be required. In-process samples and purified samples were both analysed without matrix effect issues. The assay successfully analysed heat inactivated samples and is therefore a test for potency.
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