Fig. 5.

Protection induced by the recombinant P28-19 protein was associated with the development of antigen-specific IgG responses. P28-19-specific antibody responses were measured by an ELISA using a 22-amino-acid synthetic P28-19 peptide as the antigen. Mice immunized with the recombinant E. muris P28-19 protein had higher concentrations of P28-19-specific IgG antibodies on day 14 after E. muris challenge than mice in the unvaccinated control group. Antibody responses in mice immunized with the recombinant P28-19 alone are presented for comparison. The data were expressed as means plus standard deviations, and three mice from each group were used for this analysis. OD650nm, optical density at 650 nm.