Table 5  Evaluation of RT-LAMP assay without RNA extraction step.
Dilution rate of virus
Template   10−2  10−3  10−4  10−5  10−6  10−7  Water
Direct RT-LAMP  Swab solution  Time (min)  5.5  6.0  6.8  7.5  10.5  -  -
5.3  6.0  6.8  7.3  9.0  10.5  -
5.5  6.0  7.3  7.5  9.0  -  -
Average  5.4  6.0  6.9  7.4  9.5  -  -
SD  0.1  0.0  0.2  0.1  0.7  -  -
Positive  3/3  3/3  3/3  3/3  3/3  1/3  0/3
RT-LAMP  RNA  Time (min)  4.3  5.0  5.8  6.5  7.3  -  -
5.5  6.0  7.3  7.5  9.0  -  -
4.8  5.8  6.3  6.8  7.5  9.5  -
Average  4.8  5.6  6.4  6.9  7.9  -  -
SD  0.5  0.4  0.6  0.4  0.8  -  -
Positive  3/3  3/3  3/3  3/3  3/3  1/3  0/3
Direct RT-qPCR  Swab solution  Ct value  23.14  26.47  29.86  33.43  36.40  -  -
23.22  26.50  29.87  33.29  36.93  -  -
23.01  26.46  29.75  33.28  36.96  -  -
Average  23.12  26.48  29.83  33.34  36.76  -  -
SD  0.09  0.02  0.05  0.07  0.26  -  -
copies/ reaction  1.14× 106  9.07×104  6.92×103  4.62×102  4.87×101  -  -
1.06× 106  8.84×104  6.89×103  5.12×102  3.25×101  -  -
1.25× 10−6  9.15×104  7.50×103  5.17×102  3.17×101  -  -
Average  1.15×106  9.02×104  7.10×104  4.97×102  3.77×101  -  -
SD  7.73×104  1.30×103  2.81×102  2.49×101  7.85×100  -  -
Positive  3/3  3/3  3/3  3/3  3/3  0/3  0/3
RT-qPCR  RNA  Ct value  20.89  24.29  27.76  31.13  34.70  38.95  -
20.97  24.34  27.80  31.18  34.35  37.66  -
20.75  24.28  27.65  31.00  34.51  38.16  -
Average  20.87  24.30  27.74  31.10  34.52  38.26  -
SD  0.09  0.03  0.07  0.07  0.14  0.53  -
copies/ reaction  6.23×106  4.75×105  3.41×104  2.64×103  1.77×102  7.03×100  -
5.85×106  4.56×105  3.29×104  2.55×103  2.29×102  1.87×101  -
6.93×106  4.77×105  3.72×104  2.92×103  2.04×102  1.28×101  -
Average  6.33×106  4.69×105  3.47×104  2.71×103  2.03×102  1.28×101  -
SD  4.45×105  9.44×104  1.78×103  1.56×102  2.14×101  4.78×100  -
Positive  3/3  3/3  3/3  3/3  3/3  3/3  0/3