Fig. 2. Antibody responses by the three vaccine antigen attachment ways. (A) Serum (n = 6) were taken at days 7, 14 and 24. IgG responses were detected through ELISA. (B and C) Serum (n = 6) were taken at days 24. The responses of IgG1 and IgG2a were detected through ELISA. Antibody response is expressed as the mean absorbance at 450 nm ± SD. (D) IgG2a/IgG1 ratio was calculated. *P < 0.05; **P < 0.01; ***P < 0.001.
