Safe vectors for gene therapy

摘要

The present invention provides retroviral vectors comprising direct repeats flanking a sequence that is desired to be deleted upon reverse transcription in a host cell. In a preferred embodiment the sequence that is desired to be deleted is the retroviral cis-acting encapsidation sequence (E) essential for virus production in helper cells. In gene therapy embodiments, the E sequence is deleted upon reverse transcription in target cells, thus preventing spread of retroviral vectors to non-target cells in the event of infection with replication competent viruses. The retroviral vectors of the present invention thus provide safe vectors for gene therapy.