REGULATED LENTIVIRAL PACKAGING CELL-LINE DEVOID OF MOST VIRAL CIS-ACTING SEQUENCES

Packaging cell lines derived from human immunodeficiency virus-1 (HIV- 1) are promising tools for in vivo somatic cell gene therapy protocols due to the ability of lentiviruses to infect nondividing cells. We de scribe here the generation of a safe, stable HIV-1 packaging cell line capable of expressing all of the HIV-1 structural, enzymatic, and reg ulatory proteins but lacking majority of the cis-acting sequences. The use of an inducible expression system circumvented the cytotoxic and cytostatic effects associated with the expression of some of the HIV-1 viral proteins. Reverse transcriptase activity was detectable in the supernatant from the stable packaging line 1 day after induction, whil e vector titers peaked 5 days postinduction. Vector titers of up to 3. 5 x 10(4) infectious units/ml (IU/ml) were maintained through 8 months following the establishment of the cell line. Lineage-specific gene d elivery can be achieved from this established cell line as viral stock s obtained specifically infect CD4(+) target cells. Moreover, this cel l line provides a safe and easy to use system for screening of drugs t hat inhibit HIV-1 replication. (C) 1998 Academic Press.