TABLE 3.

Comparison of threshold cycles of 38 SARS-positive samples in N-gene- and 1b-gene-specific PCR assays

Isolate	Ct for PCR		ΔCta
	N	1b
56851	27.1	27.8	0.6
55751	27.6	27.7	0.1
62290	41.9	43.2	1.3
55531	41.0	43.1	2.1
55963	41.7	42.3	0.6
65733	43.6	44.9	1.3
34862	33.5	33.7	0.2
32814	38.6	40.8	2.2
33935	35.3	36.5	1.2
34861	31.4	31.7	0.3
34862	31.9	33.2	1.3
45971	43.6	48.2	4.6
45972	43.6	46.5	2.9
45973	42.1	43.2	1.1
69145	27.2	27.7	0.5
56386	32.8	33.8	1.0
55527	37.3	39.4	2.1
56851	23.9	26.1	2.2
69073	24.3	26.1	1.3
67423	28.7	29.4	0.7
67429	35.3	35.6	0.3
67438	28.4	27.5	−0.9
68116	30.0	33.5	3.5
68118	36.7	37.7	1.0
68134	32.4	33.2	0.8
68184	30.6	32.4	1.8
68185	27.5	30.1	2.6
68187	40.3	41.5	1.2
68788	35.5	37.6	2.1
68791	34.8	35.3	0.5
68796	32.4	34.5	2.1
68798	28.8	28.4	−0.4
68800	34.6	38.3	3.7
68801	31.9	32.8	0.9
70562	40.2	43.3	3.1
70589	35.5	38.2	2.7
70591	36.0	38.2	2.2
70059	41.4	43.1	1.7

^aΔC_t, C_tlb − C_tN; average ΔC_t, 1.49 ± 0.47 (95% confidence intervals, 0.74 to 2.23, by the F test).