Table 2.
Validation of H5N1 influenza A virus recovery from large volumes of lake water and rainwater
| Type of water/country | Seeded virus strain | Date of samplinge | Expt no. | Vol of sample (liters) | Gene-specific RT-PCR | TCID50 of virus added to samplec | TCID50 recovered (%)d |
|
|---|---|---|---|---|---|---|---|---|
| Eluate | PEG concentrate | |||||||
| Lake/France | A/HK/156/97 | Oct 2008 (1) | 1 | 10 | M | 1.71 × 107 | 34.91 | 7.89 |
| H5 | 6.12 × 106 | 12.45 | 3.51 | |||||
| 2 | 10 | M | 1.71 × 107 | 17.60 | 3.26 | |||
| H5 | 6.12 × 106 | 6.27 | 1.21 | |||||
| Oct 2008 (2) | 3 | 10 | M | 9.46 × 107 | 4.37 | 0.36 | ||
| H5 | 3.38 × 107 | 4.85 | 0.22 | |||||
| 4 | 10 | M | 9.46 × 107 | 5.12 | 1.08 | |||
| H5 | 3.38 × 107 | 5.27 | 1.22 | |||||
| Nov 2008 | 5 | 10 | M | 2.66 × 103 | NDa | 1.88 | ||
| H5 | 1.70 × 103 | ND | 0.47 | |||||
| 6 | 10 | M | 2.66 × 103 | ND | 1.59 | |||
| H5 | 1.70 × 103 | ND | 1.36 | |||||
| Dec 2008 | 7 | 10 | M | 4.94 × 103 | ND | 2.25 | ||
| H5 | 8.44 × 103 | ND | 2.59 | |||||
| 8 | 10 | M | 4.94 × 103 | ND | 0.45 | |||
| H5 | 8.44 × 103 | ND | ND | |||||
| Jan 2009 | 9 | 50 | M | 2.93 × 107 | 0.20 | 0.004 | ||
| H5 | 2.52 × 106 | ND | 0.34 | |||||
| 12 | 50 | M | 4.87 × 103 | 35.52 | 2.07 | |||
| H5 | 2.21 × 103 | ND | 0.18 | |||||
| Feb 2009 | 10 | 50 | M | 5.09 × 106 | 6.95 | 0.25 | ||
| H5 | 7.76 × 106 | 1.80 | 0.35 | |||||
| 13 | 50 | M | 4.30 × 103 | 34.42 | 1.90 | |||
| H5 | 2.27 × 103 | ND | ND | |||||
| March 2009 | 11 | 50 | M | 5.88 × 106 | 8.61 | 0.80 | ||
| H5 | 4.70 × 107 | 0.29 | 0.02 | |||||
| 14 | 50 | M | 3.05 × 103 | ND | 2.50 | |||
| H5 | NDa | ND | ND | |||||
| Lake/Cambodia (Kampong Cham) | A/DK/CAM/67F8/2008 | April 2009 | 15 | 10 | H5 | 1.74 × 105 | NTb | 0.17 |
| May 2009 | 16 | 10 | H5 | 1.74 × 105 | NT | 0.49 | ||
| June 2009 | 17 | 10 | H5 | 1.74 × 105 | NT | 0.09 | ||
| July 2009 | 18 | 10 | H5 | 1.74 × 105 | NT | 0.08 | ||
| Lake/Cambodia (Prey Veng) | A/DK/CAM/67F8/2008 | April 2009 | 19 | 10 | H5 | 1.74 × 105 | NT | 1.66 |
| May 2009 | 20 | 10 | H5 | 1.74 × 105 | NT | 0.04 | ||
| June 2009 | 21 | 10 | H5 | 1.74 × 105 | NT | 0.06 | ||
| July 2009 | 22 | 10 | H5 | 1.74 × 105 | NT | ND | ||
| Rain/Cambodia | A/DK/CAM/67F8/2008 | March 2009 | 23 | 10 | H5 | 1.74 × 106 | NT | 7.57 |
| 24 | 10 | H5 | 1.74 × 106 | NT | 8.68 | |||
| 25 | 10 | H5 | 1.74 × 105 | NT | 9.31 | |||
| 25 | 10 | H5 | 1.74 × 105 | NT | 8.79 | |||
| 26 | 10 | H5 | 1.74 × 104 | NT | 3.33 | |||
| 27 | 10 | H5 | 1.74 × 104 | NT | 13.79 | |||
| 28 | 10 | H5 | 1.74 × 104 | NT | 5.98 | |||
| 29 | 10 | H5 | 1.74 × 103 | NT | ND | |||
| 30 | 10 | H5 | 1.74 × 103 | NT | ND | |||
| 31 | 10 | H5 | 1.74 × 103 | NT | 3.63 | |||
a
ND, not detected.
b
NT, not tested.
c
Results obtained by using an infectivity assay.
d
Results based upon viral quantifications by real-time RT-PCR.
e
Oct, October; Nov, November; Dec, December; Jan, January; Feb, February.