Figure 1. Seroconversion in specific-pathogen-free white leghorns after infection with influenza A/CK/CT/72/2003 (H7N2) as measured by agar gel precipitin (AGP) tests for avian influenza virus nucleoprotein and M1 antigens. Each box represents 1 chicken; (–), water; (+), water plus recombinant chicken interferon-α at 2,000 U/mL. IFN, interferon; IN, intranasal; IV, intravenous. A and B are independent trials. Serum samples were obtained at the times indicated on days post infection for overtly infected birds.