Utilization of phage display to identify antigenic regions in the PCV2 capsid protein for the evaluation of serological responses in mice and pigs
Porcine circovirus 2 (PCV2) is associated with a series of swine diseases. There is a great interest in improving our understanding of the immunology of PCV2, especially the properties of the viral capsid protein Cap-PCV2 and how they relate to the immunogenicity of the virus and the subsequent development of vaccines. Phage display screening has been widely used to study binding affinities for target proteins. The aim of this study was to use phage display screening to identify antigenic peptides in the PCV2 capsid protein. After the selection of peptides, five of them presented similarity to sequences found in cap-PCV2, and four peptides were synthesized and used for immunization in mice: 51–CTFGYTIKRTVT-62 (PS14), 127-CDNFVTKATALTY-138 (PS34), 164-CKPVLDSTIDY-173 (PC12), and 79-CFLPPGGGSNT-88 (PF1). Inoculation with the PC12 peptide led to the highest production of antibodies. Furthermore, we used the PC12 peptide as an antigen to examine the humoral response of swine serum by ELISA. The sensitivity and specificity of this assay was 88.9% and 92.85%, respectively. Altogether, characterization of immunogenic epitopes in the capsid protein of PCV2 may contribute to the improvement of vaccines and diagnostics.
Compliance with ethical standards
We thank the Brazilian Government Agencies. This research was funded by the Coordination for the Improvement of Higher Education Personnel - CAPES (grant number 23038.004678/2015-24), National Council for Scientific and Technological Development - CNPq (grant number 304727/2016-4), Foundation for Research Support of the State of Minas Gerais - FAPEMIG (grant numbers PPM-00796-15, CVZ-APQ-01327-14, CBB-RED-00005/14).
Conflict of interest
The authors declare no conflicts of interest.
This project complied with the principles of the Commission for Ethics in Animal Experimentation of the Federal University of Viçosa (UFV) under protocol n°39/2012. All authors contributed to this work and agreed to its publication.
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