Serum antibody titers and viral detection in the H5N1 HPAI virus-inoculated (group 1) and acute stage contact (group 2) ducks.

Five ducks inoculated with H5N1 HPAI virus (group 1) and five naive contact ducks (group 2) were mixed at one day post inoculation (dpi). Sera were collected at 4 days pre-inoculation for both groups and at 8 and 15 dpi (equivalent to 7 and 14 days post contact (dpc) respectively for group 2). Sera were tested with blocking ELISA (values are % inhibition; cut-off = 60%), HI using chicken RBCs (HI-C) and horse RBCs (HI-H), and virus neutralization (VN) tests. nd: not done.
a Summary of virus isolation (VI): a+symbol indicates that virus was isolated at least once from either oral or cloacal swab from the duck during the duration of the trial.
b Summary of Ct values for real-time reverse transcription polymerase chain reaction (rRT-PCR) results: the value is the lowest detected for the duck from either oral or cloacal swabs during the duration of the trial.
c Ducks 94 and 85 developed disease during the experiment; therefore the last sera were obtained when they were euthanized, for welfare reasons, at 5 dpc (shown under 8 dpi) and 9 dpc (shown under 15 dpi), respectively.