Generation of adenoviruses encoding the herpes simplex virus vhs gene: A novel strategy to generate adenoviruses expressing genes toxic to producer cells

Adenovirus vectors expressing suicide genes represent a promising approach for cancer gene therapy. We wanted to determine whether the virion host shutoff ( vhs ) gene of herpes simplex virus could be used as a suicide gene for gene therapy of glioblastomas. The vhs gene was cloned downstream of the glial fibrillary acidic protein promoter to direct tissue-specific expression, and recombinant adenoviruses were generated in 293 cells. Viruses, which contained the vhs gene but did not express it, could readily be isolated; however, we were unable to plaque purify viruses that expressed vhs protein. We constructed a derivative of 293 cells expressing an antisense RNA to the vhs gene and used them to generate adenovirus vectors that express vhs protein. These cells were used to complement vhs -expressing adenoviruses through three rounds of plaque purification. This approach could be generalized to produce adenovirus vectors expressing other toxic transgenes. Cancer Gene Therapy (2001) 8 , 566–572