Serological status, as determined by hemagglutination inhibition, of chickens 15 days after experimental pre-exposure to H7N2 LPAIV^a and 10 days after challenge with H7N1 HPAIV^b.

Sera from the animals were tested against H7 and H5 antigens. aChickens were inoculated intranasally with A/Anas plathyrhynchos/Spain/1877/2009 (H7N2) (105.5 ELD50). Serologic data from six randomly selected birds per group are presented. Due to the lack of seroconversion, only four animals from the naïve group are represented in the table. bChickens were challenged intranasally with A/FPV/Rostock/34 (H7N1) (105.5 of ELD50) 15 days after the pre-exposure to H7N2 LPAIV. cHI titers ≥8 were considered positive. dHI using antigen against H7N3 subtype. eHI using antigen against H5N1 aubtype. † = succumbed to H7N1 HPAIV-infection.