The only vaccine adjuvants approved for use in humans are aluminum gels. As aluminum is a toxic compound, even at low levels, reductions in the amount needed for each vaccine dose will be of broad health benefit. The feasability of reducing the amount of aluminum needed to potentiate the immune response to hepatitis B surface antigen (HBsAg), the active constituent of hepatitis B vaccines, has been demonstrated utilizing BIOTEK s novel mineral microspheres. In Phase II the microsphere composition will be optimized and formulations lyophilized with bound HBsAg will be prepared. The formulations will be studies as primer and booster doses in mice and baboons. PROPOSED COMMERCIAL APPLICATION The mineral microsphere adjuvant could be utilized not only in hepatitis B vaccines, now recommended for a large population including all adolescents and all health workers, but also for hepatitis A vaccine and for many components of the childhood vaccination series. This safer adjuvant could also be employed in vaccines under development, including those for AIDS. The potential for preparing lyophilized vaccine doses which would not require refrigeration generates added commercial value for the mineral microsphere adjuvants.