Table 2.
Replication and virulence of recombinant parental and reassortant CT-Sw/1204 viruses in mice
| Recombinant virusa | Stock titer (TCID50/ml) | Lung viral titer (SD)b |
MLD50c | |
|---|---|---|---|---|
| 3 days p.i. | 5 days p.i. | |||
| CT-Sw/1204 | 3.2 × 108 | 6.5 (0.5) | 6.2 (0.6) | 3.5 |
| Sw/1130HA | 5.0 × 106 | 4.8 (0.4)d | 4.5 (0.4)d | 4.8 |
| Sw/1130NA | 8.0 × 107 | 6.3 (0.6) | 6.0 (0.6) | 3.7 |
| Sw/1130PB2 | 3.2 × 107 | 5.5 (0.5)d | 5.1 (0.5)d | 4.3 |
| Sw/1130PB1 | 8.0 × 107 | 6.5 (0.5) | 6.1 (0.6) | 3.5 |
| Sw/1130PA | 1.3 × 107 | 6.0 (0.6)d | 5.6 (0.5)d | 4 |
| Sw/1130NP | 8.0 × 107 | 6.1 (0.6) | 5.9 (0.6) | 3.7 |
| Sw/1130M | 1.3 × 108 | 6.5 (0.6) | 5.9 (0.5) | 3.5 |
| Sw/1130NS | 6.3 × 108 | 6.2 (0.6) | 6.3 (0.6) | 3.8 |
| Sw/1130HA-NA | 1.3 ×107 | 5.1 (0.5)d | 4.8 (0.4)d | 5.2 |
| Sw/11303P | 6.3 × 106 | 4.5 (0.4)d | 4.1 (0.3)d | 4.7 |
| Sw/1130vRNP | 6.3 × 106 | 4.6 (0.4)d | 4.4 (0.4)d | 5.1 |
| Sw/1130 | 2.0 × 106 | 2.9 (0.30d | 2.5 (0.2)d | > 6 |
a
Reassortant virus names were assigned according to the origin of the exchanged genes (e.g., Sw/1130HA denotes a reassortant bearing the HA of Sw/1130 with the rest of its genes from CT-Sw/1204). Parental strains are in boldface.
b
Obtained from mice inoculated intranasally with 105 TCID50 of the respective viruses; titers are expressed as log10 TCID50/g.
c
Determined by inoculating mice with 102 to 106 TCID50 of virus and expressed as the log10 TCID50 required to yield 1 LD50.
d
P < 0.05 comparing virus titers relative to CT-Sw/1204-inoculated mice (two-tailed unpaired t test).