TABLE 1.

Antiviral activity of RDV and GS-441524 against SARS-CoV-2 variants

Variant	RDV plaque reduction assay (n = 3–6)		RDV nucleoprotein ELISA (n = 5–16)		GS-441524 nucleoprotein ELISA (n = 5–12)
	EC50 ± SD (nM)a	Fold change from WA1b	Mean EC50 ± SD (nM)a	Mean fold change ± SD from WA1c	Mean EC50 ± SD (nM)a	Mean fold change ± SD from WA1c
WA1	103 ± 46	1.0	110 ± 42	1.0	5,600 ± 4,100	1.0
Alpha	94 ± 58	0.92	192 ± 51	1.58 ± 0.48	8,790 ± 6,600	1.22 ± 0.60
Beta	61 ± 9	0.60	141 ± 45	1.19 ± 0.47	7,570 ± 4,400	1.13 ± 0.56
Gamma	154 ± 226	1.5	97 ± 39	0.82 ± 0.42	5,060 ± 2,300	0.79 ± 0.37
Delta	31 ± 13	0.30	70 ± 40	0.59 ± 0.20	3,260 ± 1,300	0.62 ± 0.24
Epsilon	65 ± 32	0.63	210 ± 212	1.94 ± 1.18	4,050 ± 1,700	1.27 ± 0.53
Zeta	87 ± 44	0.85	151 ± 102	1.17 ± 0.40	3,840 ± 1,400	0.93 ± 0.11
Iota	59 ± 28	0.58	258 ± 195d	2.33 ± 0.74	4,710 ± 1,600	1.43 ± 0.28
Kappa	13 ± 5	0.13	77 ± 50	0.63 ± 0.19	2,100 ± 930	0.53 ± 0.07
Lambda	94 ± 55	0.92	175 ± 138	1.37 ± 0.48	3,890 ± 1,600	0.97 ± 0.10
72 hpi
WA1	141 ± 29	1.00	95 ± 15	1.0	6,260 ± 1,200	1.0
Omicron	53 ± 32	0.37	42 ± 16e	0.45 ± 0.13	3,150 ± 1,400e	0.53 ± 0.28

^aValues are the mean ± standard deviation (SD) of the results from independent experiments. n represents the number of replicate experiments.

^bFold change calculated from the mean values = (variant mean EC₅₀)/(WA1 mean EC₅₀).

^cA fold change was calculated for each experiment, and a mean fold change ± SD was calculated with these values.

^dStatistically significant increase (P = 0.015) in EC₅₀ value of Iota in the RDV ELISA compared to the WA1 reference isolate at 48 hpi by one-way analysis of variance (ANOVA) with Bonferroni correction for multiple comparisons. All other results for variants at 48 hpi are not statistically different from the matching WA1 reference isolate.

^eStatistically significant decrease (P ≤ 0.0002) in EC₅₀ values of Omicron RDV and GS-441524 ELISA compared to the WA1 reference isolate at 72 hpi by one-way ANOVA with Bonferroni correction for multiple comparisons.