TABLE 1.
Replication and virulence of H5N1 reassortants and mutants in micea
| Virus | Mean virus titer (log10 PFU/g) ± SDb |
|||||||
|---|---|---|---|---|---|---|---|---|
| Lung |
Spleen |
Kidney |
Brain |
|||||
| Day 1 p.i. | Day 3 p.i. | Day 1 p.i. | Day 3 p.i. | Day 1 p.i. | Day 3 p.i. | Day 1 p.i. | Day 3 p.i. | |
| WT-Venus-H5N1 | 6.5 ± 0.2 | 6.3 ± 0.2 | — | — | — | — | — | — |
| MA-Venus-H5N1d | 9.1 ± 0.1c | 8.9 ± 0.0c | 3.4 ± 0.2 | 6.5 ± 0.1 | 2.4 ± 0.1 | 4.1 ± 0.1 | — | 2.8 ± 0.6 |
| rgMA-Venus-H5N1 | 9.1 ± 0.1c | 9.2 ± 0.1c | 2.8 ± 0.4 | 7.1 ± 0.0 | 2.3, —, — | 4.0 ± 0.1 | — | 2.3 ± 0.2 |
| WT+MA-PB2 | 7.7 ± 0.0c | 8.0 ± 0.1c | — | 4.1, 4.4, — | — | — | — | — |
| WT+MA-PA | 7.1 ± 0.1c | 6.8 ± 0.1c | — | — | — | — | — | — |
| WT+MA-(PB2+PA) | 8.6 ± 0.3c | 8.7 ± 0.1c | 2.9 ± 0.4 | 6.8 ± 0.0 | 2.0, 1.7, — | 4.3 ± 0.7 | — | 2.7 ± 0.8 |
| VN1203 | 8.6 ± 0.1 | 8.5 ± 0.1 | 2.9, 2.9, — | 6.4 ± 0.4 | 1.8, 2.1, — | 4.0 ± 0.8 | — | 2.9 ± 0.6 |
a
Six-week-old specific-pathogen-free C57BL/6 mice were inoculated intranasally with 105 PFU of each virus in a 50-μl volume. Three mice from each group were euthanized on days 1 and 3 p.i., and virus titers in samples of lung, spleen, kidney, and brain were determined in MDCK cells.
b
—, no virus was isolated from the sample.
c
The P value was <0.05 compared with the titers in the lungs of mice infected with WT-Venus-H5N1 virus.
d
Viral titers for MA-Venus-H5N1 virus on day 3 p.i. were reported previously (9).