TABLE 5.

Effect of HA glycosylation and the length of NA stalk on infectivity and virulence in chickens

VirusMean death time (days)a,bVirus detection in oropharyngeal swabsb
No. of positive results/totalMean titer (log10 EID50/ml)
wt A/Hong Kong/486/97 (H5N1)2.8*2/5≤1.8*
486-none-S3.3*2/5≤2.1*
486-none-L6.4**1/5≤1.3*
486-131/158/169-S3.1*5/55.3**
486-131/158/169-L3.0*5/55.1**
  • 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.