Table 1.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus concentration methods from sewage.
| Sample | Method principle | Concentration factor | Target gene | Ct before concentration* | Ct After concentration* | Lab |
|---|---|---|---|---|---|---|
| TLV1 | Concentrated using the polyethylene glycol (PEG) precipitation method. The sample was gently mixed with PEG 6000 and 0.92 g of NaCl for 12 h at 4°C | 100 | N | 35.8 | 33.1 | BGU |
| TLV2 | Glycin buffer prior to concentration in order to detach virions bound to organic material. The sample filtered through 0.22 um and virus precipitation continued using PEG 8000 (80 g/L) and NaCl (17.5 g/L) | 100 | N | 35.8 | ND | BGU |
| TLV3 | PEG precipitation (10% PEG 8000 (w/v) and 0.3 M NaCl) after pH adjustment (pH = 7.2). The pellet was extracted with chloroform | 100 | N | 35.8 | ND | BGU |
| TLV4 | Concentrated using Aluminium Sulfate. The sample was gently mixed with 20 mg/mL Alum for 12 h at 4°C | 100 | N | 35.8 | 33.6 | BGU |
| TLV5 | Folded filter paper and then concentration using Aluminium Sulfate. The sample was gently mixed with 10 mg/mL Alum for 12 h at 4°C | 50 | N | 35.01 | ND | BGU |
| TLV6 | Folded filter paper and then concentration using Aluminium Sulfate. The sample was gently mixed with 50 mg/mL Alum for 12 h at 4°C | 50 | N | 35.01 | 36.41 | BGU |
| TLV7 | Folded filter paper and then concentration using Aluminium Sulfate. The sample was gently mixed with 100 mg/mL Alum for 12 h at 4°C | 50 | N | 35.01 | 38.43 | BGU |
| TLV8 | The sample was filtered 0.22 um and then backed flash | 50 | N | 34.32 | 33.21 | BGU |
| TLV9 | Folded filter paper followed by Centricon (10 kDa cutoff) | 10 | N | 34.32 | 36.58 | BGU |
| TLV10 | Short centrifugation at 4oC, 3000g for 5 min followed by Centricon (10 kDa cutoff) | 10 | N | 34.32 | 36.85 | BGU |
| Z1 | Concentrated using the polyethylene glycol (PEG) precipitation method. The sample was gently mixed with PEG 6000 and 0.92 g of NaCl for 12 h at 4°C. Then centrifugation 4500g for 45 min and discarding the supernatant. The pellet was collected by PBS + Tween (0.05%) buffer without the chloroform step. | 50 | E | 33.37 | 33.29 | CVL |
| Z2 | Concentrated using the polyethylene glycol (PEG) precipitation method. The sample was gently mixed with PEG 6000 and 0.92 g of NaCl for 12 h at 4°C. Then centrifugation 4500g for 45 min and discarding the supernatant. The pellet was collected by PBS + Tween (0.05%) buffer without the chloroform step. | 50 | E | ND | ND | CVL |
| Z3 | Preliminary centrifugation (2500g) before precipitation method. Concentrated using the polyethylene glycol (PEG) precipitation method. The sample was gently mixed with PEG 6000 and 0.92 g of NaCl for 12 h at 4°C. Then centrifugation 4500g for 45 min and discarding the supernatant. The pellet was collected by PBS + Tween (0.05%) buffer without the chloroform step. | 50 | E | ND | 35.76 | CVL |
| Z4 | Concentrated using skim milk precipitation method. The sample was gently mixed with 0.01% (w/v) skim milk for 12 h at 4°C. Then centrifugation 4500g for 45 min and discarding the supernatant. The pellet was collected by PBS + Tween (0.05%) buffer without the chloroform step. | 50 | E | ND | ND | CVL |
*
ND, not detected/undetermined (Ct > 40).