IgG1/IgG2a (A) and IgG1/IgG2c (B) ratios calculated for TTd-specific antibodies in the sera of TTd-immunized BALB/c and C57BL/6 mice, respectively.

<p>Serum samples were collected two weeks after the completion of the immunizations and were assayed by ELISA (dilution 1∶100). Ratios were determined using the A₄₀₅ values obtained upon the measurement of TTd-specific IgG1 and IgG2a or IgG2c in sera. The results are presented as the mean A₄₀₅(IgG1)/A₄₀₅(IgG2a,c) ± SE (n = 10). The significance of the differences between syngeneic mice immunized subcutaneously with TTd (reference group) and those immunized via the conjunctiva was calculated by <i>t</i>-test (<i>P<</i>0.05*, <i>P<</i>0.005**, <i>P<</i>0.0005***).