Table 1.

Effects of 6-azauridine and cidofovir combinations on plaque numbers of vaccinia (WR strain) in Vero 76 cells.

	Cidofovir (μM)
6-Azauridine (μM)	0	8	16	32	64	128
64	0 ± 0a	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0
32	1.3 ± 2.3	1.87 ± 3.2	1.20 ± 2.1	0 ± 0b	0 ± 0	0 ± 0
16	29.5 ± 35.2	36.6 ± 42.5	19.0 ± 20.1	4.3 ± 7.5	0 ± 0	0 ± 0
8	57.6 ± 46.2	57.6 ± 46.2	46.0 ± 38.2	24.2 ± 24.3	1.4 ± 2.5	0 ± 0
4	85.1 ± 20.4	85.1 ± 20.4	68.9 ±33.2	53.4 ± 33.5	11.3 ± 10.0	0.10 ± 0.2
2	98.0 ± 3.4	98.0 ± 3.4	100 ± 0	92.1 ± 13.7	34.1 ± 27.7	0.7 ± 1.2
0	100 ± 0	99.9 ± 0.2	100 ± 0	100 ± 0	63.2 ± 16.9	5.0 ± 4.6

^aMean value ± SD (percent of plaque numbers in untreated wells), calculated from 3 independent plaque reduction assays, using three wells in each assay evaluated separately for viral plaque counts. The infectious virus dose for inoculation was an average of 80 PFU per culture for the three experiments, as determined by counts in untreated (virus control) wells.

^bThe shading indicates that the combination is synergistic at the concentrations used, as determined by a two-dimensional combination index method (Schinazi et al., 1982).