[Use of muramyl dipeptides in models of synthetic vaccines]

Vaccination represents a great success in clinical immunology and new approaches for designing vaccines of the future are now available. Protective antigens could be obtained by recombinant DNA technology or by synthesis. These new immunogens are likely to be poor immunogens and require the use of carrier and adjuvants. Both carrier and adjuvant present some limitations. In this report we consider how synthetic glycopeptides analogous to muramyl dipeptide (MDP) can be used as adjuvants under suitable conditions and can also overcome some problems due to the carrier. Muramyl dipeptides and chiefly Murabutide (NAcMur-L-Ala-D-Gln-alpha-n-butyl-ester) which is a derivative currently undergoing clinical trials can enhance the immune response to conventional purified vaccines. They can be also used in synthetic vaccines. In this case they are more active when covalently linked to the immunogen. Several examples of semisynthetic monovalent and polyvalent vaccines (Streptococcus, diphtheria toxin, Hepatitis B, Plasmodium) are described as well as totally synthetic vaccines (LH-RH, Foot-and-Mouth disease virus). They demonstrate that by using Murabutide biologically active antibodies can be produced under conditions applicable to human use.