Nanoparticle orientationally displayed antigen epitopes improve neutralizing antibody level in a model of porcine circovirus type 2

Ding, Peiyang; Zhang, Teng; Li, Yafei; Teng, Man; Sun, Yaning; Liu, Xiao; Chai, Shujun; Zhou, Enmin; Jin, Qianyue; Zhang, Gaiping

Six-week-old female BALB/c mice (~20 g) were randomly allocated to 10 groups with 4 or 8 mice per group. Each mouse was subcutaneously immunized with 100 μL of the indicated vaccines: Cap alone, Cap-AuNPs alone, Cap mixed with CpG, Cap-AuNPs mixed with CpG, Cap mixed with Carbopol 971P, Cap-AuNPs mixed with Carbopol 971P, Cap mixed with Freund's adjuvant, or Cap-AuNPs mixed with Freund's adjuvant. The AuNPs were inoculated as negative controls. We also compared the immune response of lyophilized Cap-AuNPs with non-lyophilized Cap-AuNPs. Cap-AuNPs were lyophilized and stored for 3 months at 4°C. Before immunization, Cap-AuNP powder was resuspended in water and CpG was added. One hundred μL of each corresponding vaccine mixture contained 50 μg Cap, 25 μg CpG or 2.5 μg AuNPs. The final concentration of Carbopol 971P was 0.1%. Each group received an identical booster immunization 3 weeks after primary immunization. Sera were harvested at 0, 21, and 42 days post immunization (dpi).