Fig. 4
Evaluation of the immune effect of the glycoprotein with different antigen peptides. a Model of glycogen-specific antigen presentation to T-cells. The glycoprotein is taken up by the antigen-presenting cell (APC) and digested into multiple peptides and glycan-peptides in the endosome. The peptide (red) component of the glycan-peptide is then recognized and bound by MHC-II. Finally, the glycan-peptide-MHC-II complex is transferred to the surface of the APC where it is recognized by T-cell receptors (TCRs), evoking T-cell-dependent immune responses. b The purified CTB4573H-OPS and CTB4563P2H-OPS glycoproteins were detected by Coomassie blue staining and western blot analysis against S. Paratyphi A O2 serum. Samples were derived from the same experiment and gels/blots were processed in parallel. c IL-4, IL-6, TNF-α, and IFN-γ levels were measured in the serum collected after the last immunization with CTB457H-OPS, CTB4563P2H-OPS, or adjuvant alone by ELISA (mouse IL-4, IL-6, TNF-α, and IFN-γ ELISA kit; Dakewe). A t-test was used to compare the results from the treatment groups with the expression levels of the control group (**P < 0.01; ***P < 0.001). d IgG subclass titers (IgG1, IgG2a, IgG2b, and IgG3) against SPA50973 LPS were measured in serum as described for panel c. e Complement bactericidal activity was measured in different dilutions of serum as described for panel c. Error bars indicate the standard deviation. f Two weeks after final immunization with each conjugate vaccine, mice were infected intraperitoneally with ~5.76 × 107 CFU/mouse of SPA50973 and the survival was monitored
