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. 2020 Dec 1;288:114030. doi: 10.1016/j.jviromet.2020.114030

Table 2.

Efficiency of the three qRT-PCR assays.

Assay Template Mean Ct values at quantified copy number of RNA transcript
 r2a Slopeb Efficiency (%)c
1 × 106 1 × 105 1 × 104 1 × 103 1 × 102 1 × 101
N gene assay IPBCAMS assays RNA transcriptd alone 17.63 ± 0.09e 21.99 ± 0.29 24.08 ± 0.09 28.25 ± 0.13 31.00 ± 0.06 33.73 ± 0.25 −3.19 105.82
RNA transcript + other viruses 19.40 ± 0.19 22.40 ± 0.04 26.38 ± 0.09 29.98 ± 0.07 32.17 ± 0.28 34.51 ± 0.26 −3.10 110.17
WHO assays RNA transcript alone 18.44 ± 0.19 22.65 ± 0.27 26.78 ± 0.32 29.60 ± 0.26 32.68 ± 0.15 33.97 ± 1.73 −3.16 107.23
RNA transcript + other viruses 19.51 ± 0.15 24.83 ± 0.36 26.59 ± 0.29 29.62 ± 0.54 32.62 ± 0.70 34.19 ± 0.51 −2.85 124.32
CCDC assays RNA transcript alone 17.17 ± 0.09 20.71 ± 0.11 23.94 ± 0.07 27.57 ± 0.20 30.37 ± 0.12 33.53 ± 0.50 −3.27 102.21
RNA transcript + other viruses 18.93 ± 0.16 23.79 ± 0.20 25.66 ± 0.23 29.58 ± 0.52 31.92 ± 0.16 33.81 ± 0.87 −2.93 119.43
ORF 1b gene assay IPBCAMS assays RNA transcript alone 18.64 ± 0.14 22.20 ± 0.06 25.73 ± 0.28 28.83 ± 0.37 31.90 ± 1.42 34.22 ± 1.15 −3.15 107.71
RNA transcript + other viruses 19.45 ± 0.06 22.98 ± 0.13 25.88 ± 0.17 29.37 ± 0.12 32.83 ± 0.40 34.65 ± 2.12 −3.12 109.18
WHO assays RNA transcript alone 18.51 ± 0.11 21.60 ± 0.10 25.05 ± 0.22 28.27 ± 0.12 30.78 ± 0.09 32.57 ± 0.57 −2.89 121.83
RNA transcript + other viruses 19.46 ± 0.09 22.58 ± 0.13 25.75 ± 0.19 28.20 ± 0.20 30.03 ± 0.70 33.04 ± 0.14 −2.65 138.43
CCDC assays RNA transcript alone 18.80 ± 0.31 21.96 ± 0.17 24.76 ± 0.18 28.06 ± 0.26 32.47 ± 0.79 36.16 ± 2.36 −3.48 93.80
RNA transcript + other viruses 18.67 ± 0.04 21.54 ± 0.11 24.79 ± 0.03 28.28 ± 0.04 31.09 ± 0.98 35.33 ± 0.59 −3.30 100.92
a

r2 represents the correlation of coefficient between Ct values and quantities of RNA transcripts, ranging from 0-1, the value closer to 1 suggests higher linearity of the fitting curve between Ct values and quantities of RNA transcripts.

b

Slope was generated from the fitting plot between the copy number of RNA transcript and the corresponding Ct value by Excel 2010.

c

Efficiency = 10(−1/slope) − 1.

d

“RNA transcript” represents the in vitro transcribed RNA of the corresponding genes of SARS-CoV-2. “other viruses” represents the pooled RNA extracted from 15 human respiratory specimens by using Trizol. “RNA transcript + other viruses” represents a 1:1 (v/v) mixture of these two components.

e

Values shown are the mean of triplicate samples ± standard deviation.