Fig. 5: Lipo+CPS12F& αGC induced superior high-affinity CPS12F-specific antibody production compared with other formulations.
Change of CPS12F-specific a and b IgM and d and e IgGpoly in serum and saliva after immunization. Levels of CPS12F-specific c IgM, f IgGpoly, g IgA, h IgG3, i IgG1, j IgG2b, k IgG2a in serum and saliva 2 weeks after the final vaccination. Binding rate curve for CPS12F against l serum antibody and m saliva antibody. n Dissociation constants (KD) calculated for antibodies in serum and saliva. BALB/cJRj mice were immunized with Lipo+ (group 1, blank cationic liposomes as placebo), Lipo+αGC (group 2), or 3 nmol antigen (repeat units of the polysaccharides) in Lipo+CPS12F (group 3), LipoCPS12F& αGC (group 4), or Lipo+CPS12F& αGC (group 5 & 6) via intranasal instillation (i.n., group 1–5) or subcutaneous injection (s.c., group 6) for 3 times at 2 weeks intervals. Serum and saliva were collected at the start of the study and 2 weeks after each vaccination. Antibodies inside were quantified via indirect ELISA. Their affinities were evaluated via competitive ELISA, in which the binding rate refers to the ratio of [Ab bound with suspension CPS12F]/[Ab bound with bottom CPS12F], and the KD equals the half-binding concentration of CPS12F. Rabbit antiserum against CPS12F from SSI Diagnostica was used as an external control. Data were plotted as mean ± SEM (n = 8 for a–k, DF = 29 for l–n). Curves were fitted using the one-site total binding model. Welch and Brown–Forsythe ANOVA with multiple comparisons tests were done to assess statistical significance. Group 5 was the preferred group. *, **, ***, **** represent P < 0.05, P < 0.01, P < 0.001, P < 0.0001.
