Improvement of hepatitis B vaccine by the use of a new adjuvant

Abstract

Humoral and cellular immune responses of mice and guinea-pigs to hepatitis B virus surface antigen when alum-precipitated or administered with Syntex Adjuvant Formulation (SAF) were compared. Two doses of HBsAg in SAF were sufficient to elicit antibody responses, and using SAF the dose of antigen could be reduced to one-tenth of that required to elicit antibody responses by alum-adjuvanted HBsAg. The use of SAF increased and made more consistent the antibody responses in young mice and in strains of mice with inherited low responses to HBsAg. Cellular responses to HBsAg were more consistently observed when SAF was used than when alum was used. SAF increased the formation of IgG2a antibodies in mice except in the B10.M strain; antibodies of this isotype activate complement and act synergistically with antibody-dependent effector cells more efficiently than antibodies of other isotypes. If SAF proves acceptable for human use it could improve vaccines against hepatitis B virus.