Table 2.

In vitro and in vivo characteristics of avian–human reassortant influenza viruses

Reassortant virusAvian or human virus gene*
EID50/ml, log10pfu/mlNo. of inoculated ferrets/total number
Peak nasal wash titer (day) §
PB2PB1PAHANPNAMNSWeight loss (%) Sneezing (day of onset)Virus detected in nasal wash (days p.i.)
rgVicHHHHHHHH9.35 × 106 2/3 (1.4)3/3 (2)3/3 (1–7)5.1 (1)
rg486AAAAAAAA7.55 × 105 3/3 (21.1)0/33/3 (1–7+)6.2 (5)
rgVic:486HANAHHHAHAHH7.81 × 103 1/3 (2.2)0/33/3 (1–7+)3.7 (3)
rg486:VicHANAAAAHAHAA7.84 × 106 3/3 (4.1)3/3 (2)3/3 (1–5)5.2 (3)
rg486:VicRNPHHHAHAAA7.51 × 107 2/3 (1.7)0/33/3 (1–5)4.7 (3)
rg486:VicRNPF5 HHHAHAAA8.34 × 107 3/3 (0.3)2/3 (7)3/3 (1–5)5.1 (3)
  • *Avian genes (A) are from HK486 (H5N1), and human genes (H) are from Vic75 (H3N2) virus.

  • The percentage mean maximum weight loss is shown.

  • +, the endpoint of virus detection in nasal washes was not determined for all ferrets.

  • §Peak nasal wash titers are expressed as the mean log10 EID50/ml.

  • rg486:VicRNP was passaged five times in ferrets and then grown in eggs.