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 multiple 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 construction 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 demonstrate that this vector system efficiently delivers the EBV episome and stably transforms a large fraction of infected canine D-17 cells. Using a colony-forming assay, we demonstrate stable transformation of 37% of cells that survive the infection. However, maximal transformation efficiency is achieved at doses of the El-deleted recombinant adenoviruses that are toxic to the infected cells. Consequently, E1-deleted vector toxicity imposes a limitation on our current vector system.