DNA VACCINES

DNA vaccination against infectious diseases has created a new field of applied molecular immunology. cDNAs for 'protective' protein epitopes can be inserted into vectors containing strong mammalian promoters fo r high expression. Here we discuss the mechanisms of DNA vaccination a nd the successful and sometimes unsuccessful applications of DNA vacci nation to protect animals against many different viral, bacterial myco plasmal, protozoal, and worm infections or infestations. DNA immunizat ion has been used to prevent or inhibit tumor development and to inhib it IgE responses by diverting the immune response from Th2 to Th1 help er cell dominance. Advantages and disadvantages of a variety of routes of administration and methods of immunization discussed include the u se of the 'gene gun', the delivery of genes by aerosols, and deliberat e induction of injury to muscles prior to injection of DNA to enhance gene expression. Vaccination performed using DNA without knowing befor ehand the protective epitopes, using 'expression library immunization' , is discussed. While this field is bound to expand rapidly for future clinical applications, we try to point out potential pitfalls as well as advantages of this relatively new technology.