EFFECT OF PROTEIN ADSORPTION ON THE SURFACE-CHARGE CHARACTERISTICS OFALUMINUM-CONTAINING ADJUVANTS

The effect of adsorbing two model proteins, bovine serum albumin and l ysozyme, on the point of zero charge of aluminium-containing vaccine a djuvants was studied. At physiological pH, the adsorption of the negat ively charged albumin (isoelectric point = 5.0) by aluminium hydroxide adjuvant (point of zero charge=11.1) resulted in a decrease in the po int of zero charge. In contrast, the adsorption of positively charged lysozyme (isoelectric point=9.6) by the negatively charged aluminium p hosphate adjuvant (point of zero charge=5.0) resulted in an increase i n the point of zero charge. The surface charge characteristics of the aluminium-containing adjuvant dominated at low protein coverage. In co ntrast, the surface charge characteristics of the adsorbed protein dom inated at high protein coverage. Therefore, the physicochemical proper ties of the antigen-adjuvant complex and not the adjuvant alone should be considered during vaccine preparation.