Figure 4.

CF501 adjuvant enhances the immunogenicity of the epitopes in wild-type SARS-CoV-2 RBD protein to induce bnAbs with binding specificity and activity similar to those of S309, BN03, and SA55 bnAbs in the sera of macaques vaccinated with SARS-CoV-2 RBD-Fc protein

(A) Neutralizing activity of S309, BN03, and SA55 against XBB.1.16, EG.5, and BA.2.86. Data are shown as mean ± SEM. The experiments were repeated a minimum of two times.

(B) Pooled sera from macaques immunized with CF501/RBD-Fc or Alum/RBD-Fc to block binding of SA55, BN03, and S309 to RBD from wild-type SARS-CoV-2 strain. Ro represents the highest binding signals of SA55, BN03, and S309 when pooled sera are added from macaques administered with PBS. Rc represents the highest binding signals of SA55, BN03, and S309 tested with pooled sera from CF501/RBD-Fc- or Alum/RBD-Fc-vaccinated macaques. Red, blue, and black lines represent CF501/RBD-Fc, Alum/RBD-Fc, and PBS groups, respectively.

(C) Heatmap indicates the calculated percentage of competition. Results from (Ro − Rc) × 100/Ro represent competition levels.

(D) Pooled sera from macaques immunized with CF501/RBD-Fc or Alum/RBD-Fc to block binding of SA55 and BN03 to RBD from BA.2.86. Red, blue, and black lines represent CF501/RBD-Fc, Alum/RBD-Fc, and PBS groups, respectively.

(E) Heatmap indicates the calculated percentage of competition. Results from (Ro − Rc) × 100/Ro represent competition levels.