Figure Legends
Figure 1 Antigenic cartography of EA H1N1 SIVs. Filled squares and circles represent the positions of antisera and viruses, respectively. The spacing of one gridline corresponds to an HI measurement, which equals a 2-fold difference in the HI assay. All the three axes represent antigenic distance. Strains belonging to the same antigenic cluster are encircled in a circle. Details of the HI assay data have been reported previously(Yang et al., 2016).
Figure 2 (A) Amino acid differences in HA1 protein between GX/18 and GD/104 viruses are shown as single letters at the indicated positions. Each amino acid of GX/18 is shown before the number of the position, and that of GD/104 is shown after the number of the position. (B) 3D structure of the HA protein with 9 different amino acids. The 3D structure of GX/18-HA protein is predicted by SWISS-MODEL and analyzed with PyMOL software. Different amino acids in HA1 protein are marked with different color. Residues located in antigenic site Sa are labeled as blue, site Sb as yellow, and site Ca2 as red. *, since the amino acid at position 175 is buried internally, the effect of E175R mutation on antigenicity was not evaluated.
Figure 3 The reactivity of rGX/18 viruses bearing different amino acid mutations in HA with mAb102-95. The reactivity was tested by using the HI assay and the dashed line indicates the limit of detection.
Figure 4 Structural analysis of amino acid mutation G158E. The structural change from 158G to 158E is analyzed by use of PyMOL software, and the figure only shows the difference of R group.
TABLE 1 Primers used for pBD cDNA construction and for introducing mutations into the HA gene of the reassortant and mutant viruses.