An adenovirus-Epstein-Barr virus hybrid vector that stably transforms cultured cells with high efficiency

EBV episomes are nuclear plasmids that are stably maintained through multip le cell divisions in primate and canine cells (J. L. Yates, N. Warren, and B. Sugden, Nature 313:812-815, 1985). In this report, we describe the const ruction and characterization of an E1-deleted recombinant adenovirus vector system that delivers an EBV episome to infected cells. This adenovirus-EBV hybrid vector system utilizes Cre-mediated, site-specific recombination to excise an EBV episome from a target recombinant adenovirus genome. We demo nstrate that this vector system efficiently delivers the EBV episome and st ably transforms a large fraction of infected canine D-17 cells. Using a col ony-forming assay, we demonstrate stable transformation of 37% of cells tha t survive the infection. However, maximal transformation efficiency is achi eved at doses of the El-deleted recombinant adenoviruses that are toxic to the infected cells. Consequently, E1-deleted vector toxicity imposes a limi tation on our current vector system.