Distribution of IgG subtypes IgG1 and IgG2a in immunized mice. Sera from 13 mice per group were collected from 2th week after the final immunization and the subtype levels were determined using enzyme-linked immunosorbent assays. All samples were run in triplicate. IgG subtypes IgG1 and IgG2a levels in the sera of mice two weeks after the last immunization were analyzed using an enzyme-linked immunosorbent assays. The results are representative of 3 experiments and expressed as the mean of the OD490 ± SD. *, statistically significant differences (P < 0.05) compared to the control groups.