Volume 15, Number 8—August 2009
Research
Reproducibility of Serologic Assays for Influenza Virus A (H5N1)
Table 1
Geometric mean titers (reciprocal shown) and geometric coefficient of variation for the candidate antibody standard 07/150, measured by each participating laboratory for each influenza virus*
Laboratory no. | Assay tested and virus used (phylogenetic clade) |
||||||
---|---|---|---|---|---|---|---|
hHI† |
Neutralization† |
||||||
NIBRG-14‡§ clade 1 | NIBRG-23‡ clade 2.2 | IBCDC-RG5§ clade 2.3 | NIBRG-14‡§ clade 1 | NIBRG-23‡ clade 2.2 | IBCDC-RG5§ clade 2.3 | ||
1 | 101 | 160 | 80 | 480 | 605 | 419 | |
2 | 25 | 25 | 101 | 1016 | 640 | 806 | |
3 | 403 | 320 | 160 | 1810 | 1810 | 226 | |
4 | 160 | 80 | 80 | 336 | 233 | 469 | |
5 | 406 | 256 | 256 | 450 | 270 | 632 | |
6 | 80 | 160 | 202 | 320 | 320 | 202 | |
7 | 101 | 63 | 63 | 127 | 101 | 80 | |
8 | 160 | 80 | 80 | 320 | 160 | 160 | |
9 | 160 | 183 | 115 | 160 | 52 | 80 | |
10 | 160 | 80 | 105 | 960 | 210 | 733 | |
11¶ | ND | ND | ND | 640 | 254 | 320 | |
12 | 403 | 160 | 202 | 320 | 160 | 160 | |
13 | 80 | 32 | 25 | 640 | 320 | 320 | |
14 | 160 | 127 | 25 | 2032 | 905 | 508 | |
15 |
101 |
63 |
63 |
731 |
313 |
471 |
|
Overall GMT | 140 | 102 | 91 | 518 | 291 | 299 | |
GCV, % | 112 | 109 | 101 | 120 | 140 | 109 |
*GMT. geometric mean titer; GCV, geometric coefficient of variation; hHI, hemagglutination-inhibition assay using horse erythrocytes; neutralization, virus neutralization assay; ND, not done.
†GMT neutralization vs. hHI (NIBRG-14, p = 0.003; NIBRG-23, p = 0.005; IBCDC-RG5, p = 0.005 by Wilcoxon signed-rank test).
‡GMT NIBRG-14 vs. NIBRG-23 (hHI, p = 0.039; neutralization, p = 0.004 by Wilcoxon signed-rank test).
§GMT NIBRG-14 vs. IBCDC-RG5 (hHI, p = 0.028; neutralization, p = 0.008 by Wilcoxon signed-rank test).
¶Laboratory 11 did not return hHI data.