Kristian Dalsgaard

ISCOMs and Immunostimulation with Viral Antigens

With the dissection of microorganisms followed by biochemical and immunological characterization, antigens inducing protective immunity became recognized. Early attempts to use these isolated antigens as vaccines, i.e. subunit vaccines, showed that although immunogenic in situ as part of the microorganism, they were not immunogenic as purified antigens. Subsequent studies showed that the formation of antigen into defined multimeric forms such as protein micelles or into liposomes made them considerably more immunogenic. In a way, micelles and liposomes mimic a submicroscopic particle of a microorganism with several copies of surface antigens. By contrast, monomeric forms of antigens, e.g., envelope proteins of parainfluenza-3 virus or Semliki forest virus, not only had a low immunogenicity but had a specific suppressive effect on the immune response as well; this was shown when the monomers were given simultaneously with the same antigen in a micelle (Morein et al., 1982, 1983; Morein and Simons, 1985; Jennings, 1987).