TABLE 5.
Receptor binding and replication fitness of 4c-resistant virus mutantsa
| Cloneb | Amino acid substitution(s) | No. of viral copies (RT-PCR) | HAU | CCID50 | Ratio |
|
|---|---|---|---|---|---|---|
| HAU/no. of viral copies (×1,000,000) | CCID50/no. of viral copies | |||||
| 4cr-A | R2201S, A432T, E572K | 5.0E7 | 128 | 1.1E7 | 2.5 | 0.23 |
| 4cr-B | R2201S, E572K, A962T | 3.3E7 | 176 | 5.5E6 | 5.3 | 0.17 |
| 4cr-C | D1122N | 9.3E7 | 256 | 3.2E7 | 2.8 | 0.34 |
| Control | 9.3E7 | 341 | 3.6E7 | 3.7 | 0.39 | |
a
The individual clones were expanded in eggs, and the allantoic fluids were subjected to virus titration by cell culture (expressed as the CCID50) and hemagglutination assay (expressed as the number of hemagglutinating units [HAU]). Virion quantification was done by real-time RT-PCR. The data shown are the mean of two independent tests.
b
4cr-A, 4cr-B, and 4cr-C, clones selected under 4c pressure; control, pooled data from three clones selected in the absence of compound.