Most vaccines require adjuvants for antigen stabilization and immune potentiation. Aluminum-based adjuvants are the most widely used adjuvants for human vaccines. Previous reports demonstrated the preservation of antigen conformation and other antigen characteristics after recovery from adjuvanted Hepatitis B and human papillomavirus vaccines. In this study, we used a combination of various physiochemical and immunochemical methods to analyze hepatitis E vaccine antigen quality attributes after recovery from adjuvants. All biochemical and biophysical methods showed similar characteristics of the p239 protein after recovery from adjuvanted vaccine formulation compared to the antigen in solution which never experienced adsorption/desorption process. Most importantly, we demonstrated full preservation of key antigen epitopes post-recovery from adjuvanted vaccine using a panel of murine monoclonal antibodies as exquisite probes. Antigenicity of p239 was probed with a panel of 9 mAbs using competition/blocking ELISA, surface plasmon resonance and sandwich ELISA methods. These multifaceted analyses demonstrated the preservation of antigen key epitopes and comparable protein thermal stability when adsorbed on adjuvants or of the recovered antigen post-dissolution treatment. A better understanding of the antigen conformation in adjuvanted vaccine will enhanced our knowledge of antigen-adjuvant interactions and facilitate an improved process control and development of stable vaccine formulation.
Keywords: aluminum-based adjuvant; binding analysis; capsid protein; epitope integrity; hepatitis E virus; monoclonal antibodies.