Fast and accurate determination of vaccine titer during manufacturing is important for understanding the performance of a development process and for scaling each process step. Although single radial immunodiffusion (SRID) has been the most commonly used technique for vaccine titer determination, it can be time-consuming and imprecise, requiring up to three days for results. The Pall ForteBio Octet® system offers a simple and direct method for measuring vaccine–antigen–antibody binding, capable of delivering high-precision analysis in as little as three hours.
Using the influenza virus as a model system, the relative standard deviation and dynamic range of a vaccine titer assay were measured with the Octet system and compared with results from using SRID. Polyclonal serum antibodies were loaded onto Octet biosensors, and their binding measured to epitopes presented by an inactivated virus standard to construct a standard curve. A linear range was established at 5–75 µg/mL. Vaccine samples were then measured on the Octet system and their concentration interpolated from the standard curve. Finally, vaccine titers obtained in parallel by SRID were compared with those from using the Octet system (Table 1).