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. 2021 Feb 23;12(1):e03537-20. doi: 10.1128/mBio.03537-20

FIG 2.

FIG 2

DT preexposure and vaccine immunogenicity. BALB/c mice (n = 10) were immunized i.m. with DT/Alum (3× DT prevaccination) on days 0, 21, and 28 or left unvaccinated (no DT prevaccination). Serum was collected on days 35 (1 week post last DT exposure) and 70 (5 weeks post last DT exposure) to assess DT-specific antibodies. Following DT exposure, mice were vaccinated with P*17/K4S2(DT) using the prime-pull immunization regimen. Serum samples were collected after each vaccination (up to 10 weeks) and antigen-specific antibody titers were followed by ELISA. (A) DT-specific serum IgG titers. (B) p*17-specific serum IgG titers. (C) K4S2-specific serum IgG titers. The endpoint titer was defined as the highest dilution that gave an absorbance of >3 standard deviations above the mean absorbance of negative control wells. Data are mean ± SEM of n = 10 mice/group. Statistical analysis was performed using a nonparametric, unpaired Mann-Whitney U test (one-tailed) to compare 3×DT prevaccination to the no DT prevaccination control group (ns, P > 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001). Statistical analysis and graphs were generated in GraphPad Prism 8.1.2.