EFFICIENCY OF RETROVIRAL TRANSDUCTION INTO HEMATOPOIETIC-CELLS BY COCULTIVATION PROCEDURE DOES NOT CORRELATE WITH VIRAL TITER

Relative transduction efficiency with retroviral vector-producing clon es was assayed by cocultivating TF-1, a human CD34(+) hematopoietic ce ll line and YR-2, a sheep B-lymphoid cell line, with LacZ containing v ector-producing cells, and then by scoring the percentage of X-Gal(+) cells. At the same time, viral titer was estimated by titration assay with murine fibroblasts. Results clearly demonstrated a lack of correl ation between viral titer and efficiency of transduction into hematopo ietic cells, which depends neither on the type of packaging cell line, PG-13 and GP-envAM12 in this study, nor on the type of LacZ containin g retroviral vector. These results strongly favor consideration of int eractions between producers and target cells of the study for the scre ening of producing cell lines.