TABLE 1.
Results of HI and viral neutralization assaysa
| Days after infection | Mean HI antibody titerb
|
Mean neutralization antibody titerc
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| H9N2
|
H5N1 | H9N2
|
H5N1 | |||||||
| G9 | G23 | Y280 | G1 | G9 | G23 | Y280 | G1 | |||
| 0 | <d | < | < | < | < | < | < | < | < | < |
| 3 | < | < | < | < | < | < | < | < | < | < |
| 6 | 20 | 20 | 20 | < | < | < | < | < | < | < |
| 10 | 160 | 160 | 160 | < | < | 1.25 | 1.0 | 1.0 | < | < |
| 15 | 320 | 160 | 160 | 40 | < | 2 | 1.0 | 1.25 | 1.0 | < |
| 30 | 320 | 320 | 320 | 40 | < | 2.25 | 1.5 | 2.0 | 1.0 | < |
| 70 | 320 | 320 | 320 | 40 | < | 2.5 | 2.0 | 2.25 | 1.0 | < |
| 70-booste | 640 | 640 | 640 | 160 | < | 3.75 | 2.75 | 3.50 | 1.5 | < |
Five chickens per group were infected with 103 CID50 of A/Chicken/HK/G9/97 (H9N2) influenza virus 3 to 70 days before sera were collected from wing veins. Abbreviations: G1, A/Quail/HK/G1/97 (H9N2); G23, A/Chicken/HK/G23/97 (H9N2); Y280, A/Duck/HK/Y280/97 (H9N2); G9, A/Chicken/HK/G9/97 (H9N2).
Expressed as the reciprocal of the highest dilution of serum that inhibits the hemagglutination of 4 HA units of virus.
Expressed as the reciprocal of the highest dilution of serum (log10) that neutralizes 100 TCID50 in 50% of virus-infected Madin-Darby canine kidney cells.
<, no reaction detected.
Chickens were reinfected with 103 CID50 of A/Chicken/HK/G9/97 (H9N2) 60 days after the initial infection, and 10 days later sera were collected.