Analysis of antibody responses in mice. (A) Anti-rTsNd IgG levels in the sera of immunized mice or control (MBP tag, adjuvant or PBS) mice were measured by ELISA. (B) The IgG subclass (IgG1 and IgG2a) responses in immunized mice were detected at different time point post vaccination. The OD values shown for each group are the mean ± SD of the antibody levels. The immunization time points are marked with an arrow (↓).