Table 2.
Limits of detection with cultured strains from non-VOC B.1.1 and VOCs B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta) based on virus dilution series in DMEM and saliva.
| Dilution in DMEM | ||||||
|---|---|---|---|---|---|---|
| Test | Virus Lineage | Dilution Levels (RNA copies/mL) a | ||||
| 1:10 (108/mL) |
1:100 (107/mL) |
1:1000 (106/mL) |
1:10,000 (105/mL) |
1:100,000 (104/mL) |
||
| Test I | B.1.1 (Non-VOC) | 5 | 4 | 2 | Neg. | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | Neg. | Neg. | |
| P.1 (Gamma) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 4 | 2 | Neg. | Neg. | |
| Test II | B.1.1 (Non-VOC) | 5 | 4 | 2 | 1 | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 3 | 2 | 1 | Neg. | |
| P.1 (Gamma) | 5 | 2 | 1 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 3 | 1 | Neg. | Neg. | |
| Test III | B.1.1 (Non-VOC) | 5 | 3 | 3 | 1 | Neg. |
| B.1.1.7 (Alpha) | 5 | 4 | 2 | 1 | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | 1 | Neg. | |
| P.1 (Gamma) | 5 | 4 | 2 | 1 b | Neg. | |
| B.1.617.2 (Delta) | 5 | 2 | 1 | Neg. | Neg. | |
| Test IV | B.1.1 (Non-VOC) | 5 | 4 | 2 | 1 b | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 2 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | 1 b | Neg. | |
| P.1 (Gamma) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 4 | 2 | Neg. | Neg. | |
| Dilution in Saliva | ||||||
| Test I | B.1.1 (Non-VOC) | 5 | 4 | 2 | Neg. | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | Neg. | Neg. | |
| P.1 (Gamma) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 4 | 2 | Neg. | Neg. | |
| Test II | B.1.1 (Non-VOC) | 5 | 4 | 2 | 1 | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 2 | 1 b | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | 1 | Neg. | |
| P.1 (Gamma) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 3 | 1 | Neg. | Neg. | |
| Test III | B.1.1 (Non-VOC) | 5 | 3 | 2 | Neg. | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 1 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 3 | 2 | Neg. | Neg. | |
| P.1 (Gamma) | 5 | 3 | 2 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 2 | 1 | Neg. | Neg. | |
| Test IV | B.1.1 (Non-VOC) | 5 | 4 | 3 | 1 | Neg. |
| B.1.1.7 (Alpha) | 5 | 3 | 2 | Neg. | Neg. | |
| B.1.351 (Beta) | 5 | 4 | 2 | 1 | Neg. | |
| P.1 (Gamma) | 5 | 3 | 2 | Neg. | Neg. | |
| B.1.617.2 (Delta) | 5 | 4 | 2 | Neg. | Neg. | |
The test results are described as negative (Neg., no target band visible) or as various degrees of positivity depending on the strength of the test band: (1) very faint, (2) much weaker than control band, (3) weaker than control band, (4) equally strong as control band, and (5) stronger than control band. For LoD determination, all positive bands were considered according to manufacturers’ instruction, irrespective of their intensity. a Cells shaded in grey colour indicate the dilution determining the LoD. b Only two of three replicates showed a very faint target band.