Assay     Purpose
Field flow fractionation multiangle light scattering      (FFF-MALS) Determine particle number and aggregation state
Atomic force microscopy (AFM)     Determine particle number and aggregation state
Transmission electron microscopy (TEM) Determine particle number
Size exclusion chromatography multi - angle light scattering (SEC-MALS)      Determine particle number and aggregation state
TCID, FFA, plaque, or other assays Determine proportion of defective particles based on the difference between total particles and infectious particles
Polymerase chain reaction (PCR) Determine proportion of nucleic acid containing particles
Density gradient centrifugation Determine proportion of defective particles based on relative densities of particle populations
Analytical ultracentrifugation (AUC) Determine proportion of defective and aggregated particles based on hydrodynamic properties of particle populations
Capillary electrophoresis (CE) Determine proportion of defective and aggregated particles based on particle mass and charge
Reversed-phase HPLC (RPHPLC) Determine proportion of defective and aggregated particles based on hydrophobic interaction properties
Ion-exchange chromatography (IEC) Determine proportion of defective and aggregated particles based on charge state of the particles
Size exclusion chromatography (SEC) Determine proportion of defective and aggregated particles based on hydrodynamic sieving properties of particle populations
SDS-PAGE (or equivalent) Determine composition of proteins contained in preparation based on polypeptide chain sizes
Western blot Determine composition of immunoreactive proteins contained in preparation
Process residuals (BSA, benzonase, polysorbate, etc.) Quantify process-related impurities
Table 3: Lot release and stability assays used with live viral vaccines and viral-based gene therapy products.