Table 1.

Effect of the combination of type I IFNs (IFN-α or -β) and IFN-γ on infectious virus yield in Vero cells infected with HSR1 strain

IC50 of type I IFNs obtained in combination with fixed concentrations of IFN-γ			IC50 of IFN-γ obtained in combination with fixed concentrations of type I IFNs (IFN-α or -β)
IFN-γ	IFN-αa	IFN-βa	type I IFNs	IFN-γb	IFN-γc
IU/ml	IC50, IU/ml	IC50, IU/ml	IU/ml	IC50, IU/ml	IC50, IU/ml
0	3,700 ± 650	400 ± 50	0	1,230 ± 300	1,230 ± 300
4	250 ± 80	74 ± 16	4	110 ± 21	100 ± 11
12	100 ±15	10 ± 2	12	80 ± 12	12 ± 3.4
37	40 ± 10	8.4 ± 1.3	37	50 ± 6.2	8.7 ± 2.0
111	8.3 ± 3.0	4.0 ± 1.3	111	12 ± 3.4	4.0 ± 1.1
333	2.1 ± 0.7	1.3 ± 0.8	333	4.1 ± 2.2	4.2 ± 1.3
1,000	1 ± 0.3	<1	1,000	4.4 ± 3.4	2.5 ± 1.2

All data represent means ± standard deviations of three separate experiments.

p < 0.05 as determined by Student's t test, comparison of IC₅₀ of type I IFN and IFN-γ combinations to IFN alone.

^aVero cells were treated with a fixed concentration of IFN-7 and a different concentration of IFN-α or -β and infected with SARS-CoV HSR1 (multiplicity of infection 0.1).

^bVero cells were treated with a fixed concentration of type I IFN (^b IFN-α, ^c IFN-β) and different concentrations of IFN-γ and infected with SARS-CoV HSR1 (multiplicity of infection 0.1).

^cVero cells were treated with a fixed concentration of type I IFN (^b IFN-α, ^c IFN-β) and different concentrations of IFN-γ and infected with SARS-CoV HSR1 (multiplicity of infection 0.1).