纳米颗粒展示猪圆环病毒3型Cap抗原表位的免疫效果评价OA北大核心

To verify the immune effects of nanoparticle displaying epitopes from the capsid protein(Cap)of porcine circovirus type 3(PCV3),this study screened B-cell and T-cell epitopes using peptide spot hybridization and enzyme-linked immunospot assay(ELISPOT).Epitopes were linked and displayed on the surface of E2pCD(nanoparticle display platform)using SpyCatcher/SpyTag(domains of the fibronectin-binding protein FbaB capable of forming spontaneous isopeptide bonds).Protein expression and particle assembly were detected using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and transmission electron microscopy(TEM),respectively.Enzyme-linked immunosorbent assay(ELISA)and flow cytometry were employed to evaluate the levels of PCV3 Cap antigen-specific antibodies in pig sera and peripheral blood T lymphocyte proliferation levels after immunization.The study identified 3 B-cell epitopes[P10:73-87aa(ETAISFEYYKILKMK),P21:161-175aa(QSLFFFSRPTPWLNT),P26:201-214aa(YGTKEVWIRYKSVL)]and 3 T-cell epitopes[P20:153-167aa(GTTSAHPGQSLFFFS),P21:161-175aa(QSLFFFSRPTPWLNT),P24:185-199aa(LLWSIYVPEKTGMTD)].SDS-PAGE results showed molecular weights of 40 kDa for SpyCatcher-E2pCD,16 kDa for PCV3 Cap(P10-P20～P26)-SpyTag,and 55 kDa for SpyCatcher-E2pCD-PCV3 Cap(P10-P20～P26)-SpyTag.TEM revealed the formation of nanoparticles with a diameter of approximately 22 nm for SpyCatcher-E2pCD and SpyCatcher-E2pCD-PCV3 Cap(P10-P20～P26)-SpyTag.Evaluation of immune effects demonstrated that 21 days post-immunization,specific antibody levels and proportions of CD4+,CD8+,and CD4+CD8+lymphocytes were significantly higher in pigs immunized with SpyCatcher-E2pCD-PCV3 Cap(P10-P20～P26)-SpyTag compared to PCV3 Cap(P10-P20～P26)-SpyTag(P＜0.001).These results indicate that SpyCatcher-E2pCD displaying PCV3 Cap concatenated epitopes exhibits promising immune effects,providing insights for the development of PCV3 candidate vaccines.