FIGURE 1.
Effect of swainsonine on the response of PK1, Cath.a-differentiated, LD9, and R33 cells to various prion strains. Five thousand CAD5, PK1, R33, or LD9 cells were infected in the presence (red) or absence (blue) of 2 μg/ml swa with serial dilutions of brain homogenate infected with the prions indicated for 4 days, split three times, and 20,000 cells were analyzed for PrPSc by the PK-ELISA. The vertical dotted lines indicate the dilution of brain homogenate resulting in 300 PrPSc-positive cells; the reciprocal thereof defines the RI. swa inhibited the infection of PK1 cells with RML and 79A by 2.3 logs, 22F by >1.5 logs, and 139A by 1 log and did not inhibit infection with 22L. There was no effect on infection of LD9 cells. There was a slight, but consistent, stimulation of CAD5 cell infection by RML. Each data point is the average of six measurements.