Evaluation of adjuvanticity of promising new synthetic MDP analogues

A series of nor-MDP analogues were evaluated for adjuvanticity in rodents using beta hCG-TT conjugate as the antigen. Of these, one compound, N-acetylnor-muramyl-L-N-methylalanyl-D-isoglutamine octylamide (nor-MDP octylamide (N-Me-Ala] was found to be effective. This compound, formulated with beta hCG-TT in water-in-oil emulsion and administered to rodents, significantly enhanced the anti-hCG response. The anti-hCG titers induced were three-fold higher than that of control formulation. Moreover, inclusion of this compound in the first injection only gave adequate levels of antibodies to the hormone which persisted longer in the blood circulation. Effectiveness of antibodies in neutralizing hCG was tested in vitro by the mouse Leydig cell bioassay. Biological vs. immunological binding capacities (B/I ratio) were compared. The results suggest that nor-MDP octylamide (N-Me-Ala) will be useful as an adjuvant for human vaccines.