The Construction of an Adenovirus Vector Containing Cytosine Deaminase Gene and Its Application

A replication-defective recombinant adenovirus vector containing CMV promoter and Escherichia coli cytosine deaminase (cd) gene (AdCMVCD) was constructed. It was shown by Southern blotting and RT-PCR that cd gene had been inserted into AdCMVCD and was expressed in the infected cells. The recombinant virus was purified by gradient centrifugation in CsCl and its titer was 1x10(15) pfu/L. HeLa and C6 cells infected with AdCMVCD(m.o.i=100) became sensitive to the prodrug 5FC, and the number of viable cells decreased to less than 20% of the control after treatment with 100 &mgr;mol/L 5FC. Significant bystander effect was also observed. When cells infected with AdCMVCD were mixed with wild type cells at a ratio of 3.3 : 96.7, more than 60% of the cells could be killed in the presence of 50 &mgr;mol/L 5FC. These results suggest that the AdCMVCD/5FC system may provide a new approach for gene therapy of cancers.