The biophysical characterization and the thermal stability of vaccines

The lack of vaccine thermal stability often necessitates their transport and storage at subambient temperatures. Meeting the necessary storage requirements in the developing world, however, can be difficult. The development of adequately thermostable vaccines has historically been hindered by their extreme lability and their complex structures. Thus, with few exceptions, reasons for losses in vaccine activity are not well understood.; A biophysical characterization approach was therefore employed to investigate the physical behavior of adenovirus types 2 and 5 (Ad2 and Ad5, respectively), respiratory syncytial virus (RSV), and a recombinant fusion antigen (FA) in response to pH and thermal stress. The data generated from these techniques were combined in the form of empirical phase diagrams (EPD's) to provide a more intuitive representation of the vaccine's physical stability and identify conditions (i.e., pH and temperature) under which to perform forced degradation studies in the presence of potentially stabilizing excipients.; A highly cooperative structural disruption event was observed near 45°C at neutral pH for Ad2 and Ad5. Results suggest that proteins III (the penton base) and IIIa (located in the peripentonal region) are significantly more labile than other capsid proteins and may be the initial instigators of capsid disassembly. Both serotypes of adenovirus also manifested increases in physical stability with decreasing pH from 8 to 5.; Preliminary high-throughput screening studies identified several potentially stabilizing excipients.; The biophysical characterization of RSV revealed that the secondary, tertiary, and quaternary structures of the virus are both pH and temperature labile. The best stability was observed near neutral pH.; Changes in the secondary and tertiary structures of FA, as well as increases in turbidity were most prominent below 40°C at pH 4 suggesting that the protein is least stable at this pH. The best structural stability was observed at pH 6 in the presence of 110mM NaCl.; The findings presented in this thesis demonstrate the utility of a biophysical characterization approach to elucidate common pathways of thermal degradation that most likely lead to losses in vaccine efficacy. Followed by methods of rational stabilization, this approach could ultimately lead to a dramatic reduction in morbidity and mortality of vaccine-preventable infectious diseases, especially in the developing world.