TABLE 2.
Replication and lethality of H5N1 viruses in micea
| Virus | Virus replication on day 3 p.i. (log10 EID50 ± SD)b |
MLD50 (log10 EID50)c | Attenuation (fold)f | |||
|---|---|---|---|---|---|---|
| Lung | Brain | Spleen | Kidney | |||
| DK/08 | 6.0 ± 0.5 | − | − | − | 6.2 | NA |
| CK/09 | 6.7 ± 0.5 | 3.8 ± 0.6 | 4.2 ± 0.4 | 4.0 ± 0.7 | 1.6 | NA |
| R-DK/08 | 6.0 ± 0.7 | − | − | − | 6.2 | NA |
| R-CK/09 | 7.3 ± 0.1 | 4.5 ± 0.0 | 4.5 ± 0.0 | 4.4 ± 0.1 | 1.5 | NA |
| CK/09-DK/08PB2 | 6.5 ± 0.7 | 4.5 ± 0.0 | 4.1 ± 0.7 | 4.4 ± 0.1 | 1.4 | 0 |
| CK/09-DK/08PB1 | 5.3 ± 0.4d | − | 1.5 ± 0.0d | − | 4.5 | 1,000 |
| CK/09-DK/08PA | 6.5 ± 0.3 | 4.2 ± 0.4 | 4.2 ± 0.6 | 3.8 ± 0.7 | 1.2 | 0 |
| CK/09-DK/08HA | 6.8 ± 0.4 | 3.9 ± 0.5 | 4.5 ± 0.0 | 4.2 ± 0.6 | 1.3 | 0 |
| CK/09-DK/08NP | 6.6 ± 0.8 | 4.4 ± 0.1 | 4.4 ± 0.1 | 4.3 ± 0.1 | 1.2 | 0 |
| CK/09-DK/08NA | 7.1 ± 0.5 | 4.5 ± 0.0 | 4.4 ± 0.1 | 4.5 ± 0.0 | 1.2 | 0 |
| CK/09-DK/08 M | 6.8 ± 0.6 | 3.4 ± 0.8 | 4.4 ± 0.1 | 4.1 ± 0.5 | 1.4 | 0 |
| CK/09-DK/08NS | 6.7 ± 0.3 | 4.1 ± 0.5 | 4.5 ± 0.0 | 4.0 ± 0.7 | 1.2 | 0 |
| Chimera 1 | 6.3 ± 0.4 | 3.5 ± 0.9 | 4.4 ± 0.1 | 4.2 ± 0.6 | 1.8 | 2 |
| Chimera 2 | 4.9 ± 0.3d | − | 1.4 ± 1.0d | 1.3 ± 0.9d | 4.5 | 1,000 |
| CK/09-PB1D619N | 6.6 ± 0.1 | 2.9 ± 1.4 | 4.0 ± 0.4 | 3.8 ± 0.4 | 1.4 | 0 |
| CK/09-PB1G622D | 5.8 ± 0.5d | 1.2 ± 0.8d | 2.9 ± 2.1d | 2.0 ± 1.3d | 4.2 | 501 |
| CK/09-PB1R635K | 6.5 ± 0.2 | 3.3 ± 0.9 | 3.6 ± 0.6 | 3.6 ± 0.9 | 2.5 | 10 |
| CK/09-PB1D619N+G622D | 5.3 ± 0.4 | − | 2.3 ± 0.3d | − | 4.5 | 1,000 |
| CK/09-PB1G622D+R635K | 3.8 ± 0.6e | − | 3.3 ± 0.5 | 1.3 ± 1.0e | 4.2 | 501 |
Six-week-old female BALB/c mice were used for these studies.
Groups of three mice were inoculated intranasally with 106 EID50 of the test virus in a 50-μl volume and were killed on day 3 postinoculation (p.i.); organs were then collected for virus titration in eggs. −, no virus was detected in undiluted samples. Virus titers of mice were compared by using the Student-Newman-Keuls test. SD, standard deviation.
The 50% mouse lethal dose (MLD50) was determined by intranasally inoculating groups of five mice with 10-fold serial dilutions containing 101 to 106 EID50 of virus in a 50-μl volume.
P < 0.05 compared with the titers in the corresponding organs of the R-CK/09-inoculated mice.
P < 0.01 compared with the titers in the corresponding organs of the R-CK/09-inoculated mice.
Virulence decrease compared with the R-CK/09 virus. NA, not applicable.