Figure 4. Impact of the different polybasic cleavage sites on organ distribution of AIV in the lung and brain.

Shown is the organ distribution for each virus in the lung (A) and brain (B) of birds inoculated with H03 (A–C), L01 (D–F), L11 (G–I) or L13 (J–L). Influenza virus nucleoprotein was detected by immunohistochemistry (ABC method, intranuclear and intracytoplasmic red-brown antigen signal by 3-amino-9-ethyl-carbazol chromogen and hematoxylin (blue) counterstain). Bars = 50 μm.