The competitive desorption and denaturation of model vaccine antigens
The action of the aluminum adjuvants in vaccine preparations has long been thought to be related to their action as depot sites for antigens in the interstitial fluid, which is their site of action. In this study, desorption studies were performed to determine whether the antigens are desorbed from the adjuvant surface in the body. The speed of this desorption was also studied. The strength of binding of the proteins that were used in these experiments was determined. The strength of binding on the adjuvant surfaces was determined in order to compare the binding strengths of the proteins to the desorption results seen. It was found that when model vaccine antigens were adsorbed to aluminum adjuvants, they were able to be desorbed by proteins present in the interstitial fluid. In most cases, the adsorbed antigens were substantially removed from the surface within 15 minutes or less. The factors of adsorption and desorption time were varied to determine their importance. It was found that in most cases protein was substantially desorbed in 15 minutes or less, and there was essentially no further protein desorption after 15 minutes. Adsorption of protein at concentrations above or below the adsorptive capacity of the surface affected the amount that was able to be desorbed. Adsorption of protein below the adsorptive capacity of the surface caused less protein to be desorbed, which may indicate that there was some conformational change occurring as the protein was allowed more room to spread on the surface. There was no change in the amount desorbed as the adsorption time was increased for times up to one week. It was found in all cases that the protein that had the highest affinity for the surface was able to desorb the protein with the lowest affinity, and the reverse was not seen. Studies were also performed on the possibility of conformational change in the adsorbed proteins. In all of the systems studied, conformational change was detected by internal tryptophan fluorescence for desorbed proteins. There was also UV evidence seen for several proteins studied.
Hem, Purdue University.
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