MODULATION OF GENE-EXPRESSION AFTER REPLICATION-DEFICIENT, RECOMBINANT ADENOVIRUS-MEDIATED GENE-TRANSFER BY THE PRODUCT OF A 2ND ADENOVIRUSVECTOR

To regulate gene expression following adenovirus-mediated gene transfe r, a strategy was devised utilizing co-infection with two separate ade novirus vectors designed such that the product of one vector modulated the promoter of the second vector. To evaluate this strategy, AdEGR1. TNF, an adenovirus expressing tumor necrosis factor-alpha (TNF) under the control of the early growth response 1 (EGR1) promoter, was used t o regulate a transcription unit in AdIL8.beta gal, an adenovirus vecto r in which the TNF sensitive interleukin-8 (IL-8) promoter drives the expression of beta-galactosidase (beta-gal). Following infection of HS 24 cells with AdIL8.beta gal, addition of TNF to the culture induced t he expression of beta-gal. Infection of HS24 cells with AdEGR1.TNF res ulted in a dose-dependent secretion of TNF. Little beta-gal was produc ed following co-infection of the cells with the control vector AdCMV.N ull (expressing no specific gene) and AdIL8.beta gal. In contrast, co- infection with AdIL8.beta gal and AdEGR1.TNF demonstrated, for a given dose of AdIL8.beta gal, increasing amounts of beta-gal expression dep endent on the dose of AdEGR1.TNF. This model suggests control of gene expression in adenovirus-mediated gene transfer can be regulated by ut ilizing a promoter-gene expression cassette in one vector that modulat es the expression of a promoter-gene expression cassette in a second v ector.