VARIABLE TRANSDUCTION EFFICIENCY OF MURINE LEUKEMIA RETROVIRAL VECTORON MAMMALIAN-CELLS - ROLE OF CELLULAR GLYCOSYLATION

To elucidate the cellular tropism of Moloney murine leukemia virus (Mu LV), we have studied the transduction efficiency of a recombinant MuLV vector carrying the beta-galactosidase reporter gene on a variety of rodent cells. Under optimal conditions for in vitro cell transduction, primary cultures of adult rat fibroblasts derived from various organs were very poorly transduced by the ecotropic MuLV vector (0.02-0.12%) when compared to immortalized cells such as the F2408 (42%) and 3Y1 ( defined as 100%) lines. Primary cultures of fibroblasts from neonatal (3.7%) or embryonic rat tissues (4.6%) and primary cultures of rat mam mary epithelial cells (3-4%) were somewhat more susceptible. Immortali zation of rodent fibroblasts with Polyomavirus Large T, SV40 Large T, and E6-E7 genes of human papilloma virus resulted in a modest or minim al increase in transduction efficiency, and introduction of the transf orming genes v-Src, v-Ras, and v-Raf was in most instances associated with a decrease in MuLV vector entry. Variability of transduction effi ciency was not related to differences in cellular growth rate and trea tment of MuLV vectors in vitro with deoxyribonucleoside triphosphates and treatment of cells in culture with protease inhibitors failed to m odify cellular entry of the MuLV vector. On the other hand, inhibition of cellular glycosylation with swansonine, 1-deoxymannojirimycin and, primarily, tunicamycin enhanced entry of the ecotropic vector by up t o 220-fold, particularly into cells which were otherwise highly resist ant These findings demonstrate major differences in transduction effic iency of the ecotropic MuLV vector on rodent cells and indicate that c ellular glycosylation plays a critical role in determining MuLV cellul ar tropism. (C) 1997 Academic Press.