Polynucleotide vaccines: potential for inducing immunity in animals

Polynucleotide immunization has been described as the Third Revolution in V accinology. Early studies suggest the potential benefits of this form of im munization including: long-lived immunity, a broad-spectrum of immune respo nses (both cell mediated immunity, and humoral responses) and the simultane ous induction of immunity to a variety of pathogens through the use of mult ivalent vaccines. Using a murine model, we studied methods to enhance and d irect the immune response to polynucleotide vaccines. We demonstrated the a bility to modulate the magnitude and direction of the immune response by co -administration of plasmid encoded cytokines and antigen. Also, we clearly demonstrated that the cellular components (cytosolic, membrane-anchored, or extracellular) to which the expressed antigen is delivered determines the types of immune responses induced. Since induction of immunity at mucosal s urfaces (route of entry for many pathogens) is critical to prevent infectio n, various methods of delivering polynucleotide vaccines to mucosal surface s have been attempted and are described. Expansion of studies in various sp ecies, using natural models, should be extremely helpful in demonstrating t he universality of this approach to immunization and more importantly, accu rately identify parameters that are critical for the development of protect ive immunity. (C) 1999 Elsevier Science B.V. All rights reserved.