Serum antibodies and viral detection in the H5N1-infected (group 3) and post acute stage contact (group 4) ducks.

Ten ducks (group 3) inoculated with H5N1 HPAI virus were mixed with nine naive contact ducks (group 4) at 10 day post inoculation (dpi). Sera were collected at 4 days pre-inoculation for both groups and at 8, 15, 22, 29, and 34 dpi for both groups, which corresponded to 12, 19 and 24 days post contact (dpc) for group 4. Sera were tested using blocking ELISA (values are % inhibition; cut-off = 60%), HI with 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 an 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.