TABLE 5.
Effect of HA glycosylation and the length of NA stalk on infectivity and virulence in chickens
| Virus | Mean death time (days)a,b | Virus detection in oropharyngeal swabsb
|
|
|---|---|---|---|
| No. of positive results/total | Mean titer (log10 EID50/ml) | ||
| wt A/Hong Kong/486/97 (H5N1) | 2.8* | 2/5 | ≤1.8* |
| 486-none-S | 3.3* | 2/5 | ≤2.1* |
| 486-none-L | 6.4** | 1/5 | ≤1.3* |
| 486-131/158/169-S | 3.1* | 5/5 | 5.3** |
| 486-131/158/169-L | 3.0* | 5/5 | 5.1** |
a
Mean death time and viral shedding by RT-PCR in samples collected 3 days postinfection in chickens intranasally inoculated with 10 50% chicken lethal doses of the indicated virus.
b
Different number of asterisks indicate statistically significant differences between treatment groups (P ≤ 0.05) after pairwise comparison using the t test or the Mann-Whitney rank sum test, depending on data normality.