Efficient in vitro and in vivo excision of floxed sequences with a high-capacity adenoviral vector expressing Cre recombinase.

Conditional gene expression or gene disruption using Cre/loxP- or FLP/frt-based recombination systems are valuable tools for studying gene function in development and disease. Recombinant adenoviral vectors expressing Cre recombinase have been suggested as an alternative for deletion of floxed sequences. To further improve this approach we generated a high-capacity adenoviral (HC-Ad) vector expressing Cre (HC-Adcre). In this vector all viral coding sequences are deleted resulting in decreased toxicity. In the present study HC-Adcre efficiently mediated recombination between two loxP sites located in the genome of a reporter cell line. When intravenously injected into ROSA26 reporter mice, a floxed sequence was excised in hepatocytes resulting in expression of the beta-gal reporter. Our data indicate that HC-Ad vectors expressing Cre effectively delete floxed sequences in vivo and have a significant potential as a tool for functional studies in mice.