IN-VIVO MODEL OF ADENOASSOCIATED VIRUS VECTOR PERSISTENCE AND RESCUE

Gene therapy vectors based on human DNA viruses could be mobilized or rescued from individuals who are subsequently infected with the corres ponding wild-type (wt) helper viruses. This phenomenon has been effect ively modeled in vitro with both adenovirus (Ad) and adeno-associated virus (AAV) vectors but has not previously been studied in vivo. In th e current study, we have developed an in vivo model to study the inter actions of a recombinant AAV vector (AAV-CFTR) with wt AAV type 2 (AAV 2) and a host range mutant Ad (Ad2HR405) for which monkey cells are pe rmissive (D. E. Brough, S. A. Rice, S. Sell, and D. F. Klessig, J. Vir ol. 55:206-212, 1985), AAV-CFTR was administered to the respiratory ep ithelium of the nose or lung of rhesus macaques. Primary cells were ha rvested from the infusion site at time points up to 3 months after vec tor administration to confirm vector DNA persistence. Vector DNA was p resent in episomal form and could be rescued in vitro only by addition of wt AAV2 and Ad. In in vivo rescue studies, vector was administered before or after wt-AAV2 and Ad2HR405 infection, and the shedding of A AV-CFTR was examined. Ad2HR405 and wt-AAV2 infections were established in the nose with concomitant administration. wt-AAV2 replication occu rred in the lung when virus was administered directly at a high titer to the lower respiratory tract. AAV-CFTR vector rescue was also observ ed in the latter setting. Although these studies were performed with s mall numbers of animals within each group, it appears that AAV-CFTR DN A persists in the primate respiratory tract and that this model may be useful for studies of recombinant AAV vector rescue.