Old and new vaccine approaches.

The conventional, currently available vaccines, though quite successful, suffer from a few shortcomings which hamper future vaccine development. We present herewith some of the new approaches that are presently being pursued, including (1) the development of recombinant, or genetically engineered, vaccines which are based either on the expression of the relevant protective antigen and its formulation into vaccine, or the production of live vaccines, where an appropriate live vector (virus or bacterium) presents the foreign antigen. (2) The development of naked DNA vaccines that include the gene(s) coding for the relevant protective antigen(s). (3) Peptide vaccines that include defined B cell and T cell epitopes, either in a chemically synthesized molecule or in a synthetic recombinant construct. The efficacy of such vaccines is usually dependent on adequate presentation and delivery, namely, carrier/adjuvant technology. (4) Therapeutic vaccines, based on all of the above approaches, may be applied for chronic or long-term infections, or for noninfectious diseases including autoimmune diseases, various neurological disorders, allergy and cancer.