Fig. 4
From: The molecular determinants of antigenic drift in a novel avian influenza A (H9N2) variant virus
Three-dimensional (3D) antigenic maps of AH/17 and FJ/20 chimeras and reference viruses. The scale bar in each map represents 1 antigenic unit (1 antigenic unit corresponds to a twofold dilution of antiserum in the HI assay). A The antigenic distance between AH/17 and FJ/20, AH/17_Chim_III. B The antigenic distance between FJ/20 and FJ/20_Chim_III, AH/17_Chim_III, AH/17 and FJ/20_Chim_III