Construction of new retroviral producer cells from adenoviral and retroviral vectors.

A combination of adenoviral and retroviral vectors was used to construct second generation packaging cells that deliver marker genes to target cells. A vector based upon Moloney murine leukemia virus (MoMLV) was used to deliver marker genes, and an adenovirus-based delivery system was used to deliver MoMLV structural genes (gag pol and env) to cultured cells. The procedure transformed the cells into new retroviral producer cells, which generate replication-incompetent retroviral particles in the culture supernatant for transferring marker genes to target cells. The titer of the retroviral-containing supernatant generated from the second generation producer cells reached above 10(5) c.f.u./ml, which is comparable to the MoMLV-based producer cell lines currently used in human gene therapy trials. These observations suggest that this new gene transfer scheme is technically feasible. The vector and procedures may be adapted for experimental human gene therapy in which the new producer cells are transplanted into patients for continuous gene transfer.