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

Uptake by APCs is the initial step for an antigen to arouse an immune response. 37 We evaluated the uptake level of Cap protein using RAW264.7 cells and DC2.4 cells, which are often used as a model for primary macrophages and DCs, respectively. Additionally, antigen internalization, cytotoxicity, and cytokine release are size dependent. After incubation for 1 h, the Cap protein uptake by APCs was detected by IFA, and the fluorescence intensity corresponded to the number of Cap protein within APCs. As seen in Figure 4A , compared to the Cap protein group, the Cap-AuNP group had higher fluorescence intensity. More Cap protein was internalized when Cap protein was adsorbed on AuNPs ( Figure 4B ). These data suggested that the 23 nm diameter AuNPs improved the amount of Cap protein internalized into the APCs, and the Cap protein distributed in the cytoplasm, not the nucleus.