Fig. 1.
Selection of RU clones from the U937 cell line. Starting with 106 U937 cells, three successive rounds of infection with parvovirus H-1 were performed at a MOI of 100 pfu/cell. Cell viability was determined microscopically 4 days after infection, using the Trypan blue dye (0.2%) exclusion procedure. Only subclones displaying a survival to H-1 virus infection higher than 50% were considered. Four clones (RU1-4) whose resistance to H-1 infection was above 90% were selected.
