GENERATION OF HIGH-TITER RETROVIRAL VECTORS FOLLOWING RECEPTOR-MEDIATED, ADENOVIRUS-AUGMENTED TRANSFECTION

A new procedure is described for the generation of high-titer helper-f ree retrovirus vectors employing receptor-mediated, adenovirus-augment ed transfection into a standard packaging cell line. Viral titers are increased 30-fold to 100-fold in transiently (>10(5) infectious units per mt) and stable (>10(7) infectious units per mt) transfected cells as compared with either CaPO4-mediated transfection or retroviral infe ction of a packaging cell line. Further expression of the transduced g enes was drastically increased in the transfected cells, but, as expec ted, there was no difference in transduction efficiency and gene expre ssion in the infected target cells. The increases in viral titers were most likely due to the high number of stable, integrated copies of th e vector plasmid DNA in the resulting packaging lines following G418 s election. In addition, experiments generating recombinant retroviruses from non-packaging cell lines are presented. The results suggest that this procedure may be of use to generate high-titer retrovirus vector s in packaging cell lines as well as in primary cells, thus providing a technical basis for in vivo gene transfer upon transplantation of th ese cells into various organs.