Fig. 1From: Ducks induce rapid and robust antibody responses than chickens at early time after intravenous infection with H9N2 avian influenza virusAntibody response in chickens and ducks intranasally infected with the H9N2 virus. a A hemagglutination inhibition (HI) assay was performed to test the serum samples of birds at the indicated time points (HI > log24 was considered positive). b A blocking ELISA was used to test the serum samples of birds at the indicated time points (PI > 25% was considered positive; **, p < 0.01)Back to article page