Table 5.
i.p. injection with | HRBC HI GMT* | |||
Prevac† | 4 wpv | 3 wpb | 2 wpc | |
PBS | <10 (0/9) | 49 (7/9) | 86 (9/9) | 101 (9/9) |
1:100-diluted sera | <10 (0/9) | 59 (9/9) | 137 (9/9) | 209 (9/9) |
1:10-diluted sera | <10 (0/9) | 31 (8/9) | 80 (9/9) | 137 (9/9) |
Undiluted sera | <10 (0/9) | 17 (4/9) | 47 (8/9) | 49 (7/7) |
Control‡ | <10 (0/9) | <10 (0/9) | <10 (0/9) | ndd |
Prevac, prevaccination; wpv, weeks postvaccination; wpb, weeks postboost; wpc, weeks postchallenge; nd, not determined because of death.
*Boost vaccination with YEBIO H5N1 Re-1 vaccine occurred 4 wk after initial vaccination, and challenge with the lethal Ck/Qal-Egypt/1/08 (H5N1) virus occurred 3 wk later. HI titers against challenge virus (Ck/Qal-Egypt/1/08 [H5N1]) are the reciprocals of the highest dilutions of sera that inhibited hemagglutination by 4 HA units of virus. The results are the geometric mean titers of positive sera (≥10). Values in parentheses are number of chickens with positive sera/total number.
†The prevaccination samples were collected from 1-wk-old chickens on the day before i.p. injection of H5 antibodies.
‡Chickens were immunized passively with pooled anti-H5 chicken sera but not vaccinated before challenge.