Fig 1: The location and density of GPV antigen, CD4 and CD8a molecules in the liver (LI), lungs (LU), small intestine (SI), and rectum (R).Geese were humanly killed 5 days post infection by viruses. The protein locations in the different tissues of H9N2-infected birds were detected by IHC assay. Positive virus signals were detected, cells positive for CD4 or CD8a antigen appeared dark brown using immunohistochemical staining, and sections were counterstained with haematoxylin. Mouse polyclonal antibody against GPV was prepared by our laboratory. The dilution folds of mouse anti-duck monoclonal CD4 antibodies (AbD Serotec MCA2478) and mouse anti-goose monoclonal CD8a (provided by our laboratory) antibodies were 1:100, respectively. Incubation with goat anti-mouse or goat anti-rabbit secondary antibody was performed according to the protocols of the immunoassay kit. Liver (A,E,I), lungs (B,F,J), small intestine (C,G,K) and rectum (D,H,L).