Adjuvants designed for veterinary and human vaccines

Adjuvants play an important role in the efficacy of vaccines as the antigen s become more and more purified. Indeed recombinant proteins or synthetic p eptides are safer than crude inactivated micro-organism, but less immunogen ic. This can be balanced by specific adjuvants. But there is no universal a djuvants and their action is not vet clear and rely on different mechanisms . Then, they must be adapted according to several criteria, like the target species, the antigens. the type of immune response, the route of inoculati on, or the duration of immunity. For this purpose different type of emulsio ns have been developed. Water in oil (W/O) emulsions induce a strong and lo ng term immune response. Those based on mineral oils are known to be very e fficient but can sometimes induce local reactions with reactive antigens. N on mineral oils are well tolerated but less efficient with poor immunogens. Multiphasic (W/O/W) emulsions can induce short and long term immune respon ses with various antigens and oil in water (OW) emulsions are well tolerate d and induce a short term immune response. New generation of adjuvants are based on a new concept called 'immunosol' and stem from the association of nanoparticles with a new immunostimulant. They can be used when emulsions a re not suitable to obtain a good balance between safety and immunogenicity. (C) 2001 Elsevier Science Ltd. All rights reserved.