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

Vaccines are typically co-administered with adjuvants. In order to explore whether AuNPs are capable of enhancing NA levels by orientationally displaying epitopes in different types of adjuvants, we used three different types of adjuvants. CpG, a widely used soluble Th1-type adjuvant, is the ligand of TLR9 that recognizes pathogen-associated molecular patterns on foreign pathogens. Carbopol, a water-like substance, lightly cross-linked polymer of acrylic acid, has become a widely used adjuvant. Freund's adjuvant, an oil-like substance, is the most commonly used adjuvant in animal experiments. 40 We used these three representative adjuvants in the current study. As shown in Figure 6 , AuNPs significantly increased the Cap-specific antibody levels in the no-adjuvant and CpG groups, while there was almost no effect in the Carbopol and Freund's adjuvant groups ( Figure 6A ). We used the purified inactivated virus as fixative to detect PCV2-specific antibody levels. These antibodies bind to the outer surface of