Fig. 4
In vivo immune responses of injected UC peptides and complement activity of immunized serum. (a) BALB/c mice were intramuscularly administered 3 doses of 50 µg of UC-100 (n = 3) or 400 µg of UC-152 (n = 4) 14 days apart. (b–d) The serum of UC-100 mice was collected pre-(Day-1) and posttreatment (Day41) and tested in duplicate and represented as the mean for the levels of (b) total IgG; (c) specific IgG against UC-100 peptide; (d) specific IgG against SARS-CoV-2 spike trimer protein. (e–g) The serum of UC-152 mice was collected pre-(Day-1) and posttreatment (Day41) and tested in duplicate and represented as the mean for the levels of (e) total IgG; (f) specific IgG against UC-152 peptide; (g) specific IgG against SARS-CoV-2 spike trimer protein. (h,i) Antibody-mediated complement activity was tested in duplicate and is represented as the mean for pre- and postserum of mice vaccinated with UC-100 and UC-152 peptides, respectively. The complement activity was expressed as the IC50 of cytotoxicity of the (h) UC-100-vaccinated group and (i) UC-152-vaccinated group. Significant differences are indicated by asterisks (unpaired one-tailed Student’s t test; *p < 0.05, **p < 0.01, ***p < 0.001).
