Production of viral vectors with suicide genes by utilizing the intron-splicing mechanism of insect cells

Viral vectors carrying suicide genes such as diphtheria toxin, Pseudomonas exotoxin, or barnase are very useful tools in cancer gene therapy and cell ablation research. However, such viral vectors are extremely difficult to produce due to the fact that trace amounts of the toxin will kill any cells used for viral vector production. To overcome this obstacle, we inserted mammalian introns that are not recognized by insect cells to break up the open reading frames (ORFs) of the toxic genes and successfully produced at normal levels of baculoviral and adeno-associated viral (AAV) vectors carrying these toxic genes. Once these viral vectors were used to infect mammalian cells, the introns were spliced out and toxic proteins expressed to kill the target cells.