FIG. 4.

DIVA serology with marker ELISAs. Sera taken from animals 3 weeks (21 days postimmunization) and 6 weeks (42 days postimmunization) after immunization and 10 days after challenge infection (10 days postchallenge) were tested with commercially available ELISAs specific for HA5 (A), NA1 (B), and NP (C), respectively. Average values for each group (“herd level”) are given as percent inhibition and are represented as a bar. Values above 40% inhibition (HA5 ELISA), 60% inhibition (N1 ELISA), or 65% inhibition (NP ELISA) scored negative. These threshold values are indicated by a horizontal line.