ASSAYS FOR ADJUVANTICITY OF NEW FORMULATIONS AND OF CARRIER PROTEINS FOR INDUCING ANTIBODY-RESPONSES TO SELECTED IMMUNOGENS IN THE SQUIRREL-MONKEY SAIMIRI-SCIUREUS

Different ways to improve antibody (Ab) responses following immunizati ons with selected antigens (TT and HSVgD) were investigated, and thus new adjuvant formulations and carrier molecules in a non-human primate experimental host, the squirrel monkey Saimiri sciureus, were assayed . Both quantitative and qualitative humoral responses were determined by means of radio-immunoassays using monoclonal Ab directed at Saimiri IgG. First, the adjuvanticity of the Syntex (SAF-1) adjuvant and of f ive new adjuvant formulations were assessed towards the selected Ag. T his indicated that all the adjuvants induced similar antigen-specific Ab responses, although the adjuvants could modify to some extent the p attern of the qualitative Ab response. Second, we evaluated an adjuvan t-free vaccine approach using a synthetic Ag from the circumsporozoite protein of Plasmodium falciparum as immunogen, this Ag being coupled to purified protein derivative (PPD) or to a recombinant heat shock pr otein from Mycobacterium tuberculosis. These constructs led to good an tibody responses as well as an excellent memory effect. Bacille Calmet te-Guerin (BCG) priming was required in conjunction with PPD as a carr ier molecule to allow homogeneous Ab responses, whereas the heat shock protein construct gave a less homogeneous Ab response regardless of w hether a BCG priming was done. We, in addition, discuss the relevance of Saimiri monkeys as experimental models for studies directed at eval uating the immunogenicity of further vaccine candidates.