Abstract
OBJECTIVES: Several vaccine adjuvants comprise complex nano- or micro-particle formulations, such as oil-in-water emulsions. In order to characterize interactions and compatibility of oil-in-water emulsion adjuvants with protein antigens in vaccines, effective protein characterization methods that can accommodate potential interference from high concentrations of lipid-based particles are needed. METHODS: Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is a standard protein characterization technique which is affected by the presence of adjuvants such as oil-in-water emulsions. In this article, we investigate variations in SDS-PAGE methods that result in a reduction of adjuvant-induced staining artifacts. We have investigated whether the SDS method or the adjuvant composition were the reason for these artifacts and succeeded in reducing the artifacts with a modified sample preparation and different staining procedures. RESULTS: The best results were obtained by using gold staining or silver staining instead of a Coomassie Blue staining procedure. Moreover, the replacement of the dilution buffer (20% SDS to disrupt emulsion) by alternative detergents such as Tween® 80 and Triton® X-100 removed adjuvant-induced streaking artifacts at the top of the gel. CONCLUSIONS: These methods may be useful for improving characterization approaches of antigen-adjuvant mixtures by SDS-PAGE.