Generation of a stable cell line producing high-titer self-inactivating lentiviral vectors

To facilitate the generation of SIN lentivirus vector-producer cell lines, we have developed a novel conditional SIN (cSIN) lentivirus vector, which r etains its SIN properties in normal target cells yet can be produced at hig h titers from tetracycline-regulated packaging cell lines. The design of th e cSIN vector is based on replacing the vector U3 transcription regulatory elements with the Tet-responsive element, which allows vector production ex clusively in cells expressing the synthetic Tet-regulated transactivator (t TA). In contrast minimal vector production (similar to 200 IU/ml) is obtain ed in target cells that do not express the tTA, even in the presence of all HIV-1 proteins. Following transduction of the Tet-regulated SODk1 lentivir us vector-packaging cell line with the cSIN vector, high titers of cSIN rec ombinant vector (>10(6) IU/ml) could be generated, which efficiently transd uced terminally differentiated neurons in normal rat brain.