Research Project
6404017
The goal of this program is the optimization and evaluation of an adjuvanted therapeutic DNA vaccine strategy for AIDS using the rhesus monkey/SIV model system. In addition, a graduated clinical evaluation approach is planned to introduce this technology into the clinic in a stepwise manner. The DNA vaccine to be employed will encode the full length gag, pol, and env products of SIV as well as a series of defined CTL epitopes fused to an immunogenic carrier protein. The novelty of our approach centers on the inclusion of an adjuvant vector encoding the A and B subunits of cholera toxin (CT) or the E. coli heat labile enterotoxin (LT) to augment antigen-specific Th1 immunity and systemic and mucosal CTL responses. The adjuvanted DNA vaccine will be formulated onto microscopic gold particles and delivered to the skin as a therapeutic vaccine using a clinical "gene gun" device. Elucidation of the mechanism of adjuvant action will be assisted by the analysis of chemokine involvement and the activation and trafficking of dendritic cells. Justification of the proposed approach is based on three important findings from our laboratories: 1, Human clinical evaluation of a "gene gun"-based DNA vaccine for hepatitis B resulted in the induction of vigorous antigen-specific, Th1 and cytotoxic cellular immune responses in humans, confirming the clinical effectiveness of this means of DNA vaccine delivery. 2, The induction of SIV-specific CTL responses via gene gun-based DNA vaccination in the rhesus/SIV model provides measurable protection from challenge with pathogenic SIVdeltaB670. 3, The formulation of DNA vaccines with vectors encoding eith4r CT or LT results in marked and surprising enhancements of Th1 and CTL responses without any evidence of local or systemic toxicity in small and large animals. Clinical development of the adjuvanted DNA vaccine approach will take place in a graduated manner involving initial evaluation of a single HIV therapeutic DNA vaccine vector in a small phase I/II trial. A second clinical trial attempting to establish clinical proof of concept of the adjuvanted DNA vaccine approach will follow. The later trial will include the addition of a vector encoding CT or LT.
