Table 2. Antiviral activity (IC₅₀ and IC₉₀) of RBV against VSV and SeV in different cell types.

Cell type	IC50 (µM)	IC90 (µM)	IC50 (µM)	IC90 (µM)
	VSV-GFP		SeV-GFP
BHK21	275	1100	190	850
BSRT7	10	40	16	40
HeLa	70	150	40	110
A549	190	610	90	320
4T1	20	60	10	18
HEp2	70	310	12	45
Vero	2250	>3000	1550	>3000

The 50% and 90% inhibitory concentrations (IC₅₀ and IC₉₀) for RBV were estimated by means of the plaque reduction (Fig. 2) as described in Materials and Methods. Data are expressed as mean without standard error of mean that, however, never exceeded 20% of the mean values. Note that an extremely poor potency of RBV against VSV and SeV in Vero did not allow it to reach IC₉₀ even at 3000 µM RBV concentration (“>3000”).