Fig 6.
vtHBsAgs with amino acid substitutions at position 145 or 122 had reduced ability to induce anti-HBs antibody response. BALB/c (H-2 Ld) mice were immunized with 30 μg of the expression plasmid pHBsAgWT (n = 8), pHBsAgG145I (G145I) (n = 6), pHBsAgG145E (G145E) (n = 6), pHBsAgG145W (G145W) (n = 6), pHBsAgG145R (G145R) (n = 10), pHBsAgK122L (K122L) (n = 6), pHBsAgK122I (K122I) (n = 6), or with 30 μl of PBS (n = 10) as a control. The immunizations were given three times within 3-week intervals. Sera were collected and tested for anti-HBs antibodies at day 10 after the last immunization. Results are shown as the anti-HBs IgG (mIU/ml) level for each mouse per group. Filled circles represent IgG titers in individual mice. Solid lines represent geometric mean values. The dotted line represents the cutoff, which was assumed to be 2.1-fold the mean value of the negative samples.