title: Characterization of specific antigenic epitopes and the nuclear export signal of the Porcine circovirus 2 ORF3 protein.
abstract: Porcine circovirus 2 (PCV2) is the etiological agent of postweaning multisystemic wasting syndrome. PCV2 ORF3 protein is a nonstructural protein known to induce apoptosis, but little is known about the biological function of ORF3 protein. Therefore, we undertook this study to map ORF3 protein epitopes recognized by a panel of monoclonal antibodies (mAbs) and to characterize putative nuclear localization (NLS) and nuclear export (NES) sequences in ORF3. The linear epitopes targeted by two previously published mAbs 3B1 and 1H3 and a novel mouse mAb 3C3 were defined using overlapping pools of peptides. Here, we find that ORF3 in PCV2 infected cells contains a conformational epitope targeted by the antibody 3C3, which is distinct from linear epitopes recognized by the antibodies 3B1 and 1H3 in recombinant ORF3 protein. These results suggest that the linear epitope recognized by 3B1 and 1H3 is masked in PCV2 infected cells, and that the conformational epitope is unique to PCV2 infection. Furthermore, we find that ORF3 protein expressed in cytoplasm in early stages of PCV2 infection and then accumulated in nucleus over time. Moreover, we localize a NES at the N-terminus (residues 1-35aa) of ORF3 which plays critical role in nuclear export activity. These findings provide a novel insight that deepens our understanding of the biological function of PCV2 ORF3.
authors: Institute of Immunity and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, PR China.
authors: Jinyan
authors: J
authors: Gu
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China.
authors: Lun
authors: L
authors: Wang
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China.
authors: Yulan
authors: Y
authors: Jin
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China.
authors: Cui
authors: C
authors: Lin
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China.
authors: Huijuan
authors: H
authors: Wang
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China.
authors: Niu
authors: N
authors: Zhou
authors: Institute of Immunity and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, PR China.
authors: Gang
authors: G
authors: Xing
authors: Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China. Electronic address: liaomin4545@zju.edu.cn.
authors: Min
authors: M
authors: Liao
authors: Institute of Immunity and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, PR China; Key Laboratory of Animal Virology, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, PR China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University, Hangzhou 310058, PR China. Electronic address: jyzhou@zju.edu.cn.
authors: Jiyong
authors: J
authors: Zhou
mesh_terms: D000818:Animals; D002460:Cell Line; D018173:Circoviridae Infections / Q000503:physiopathology*; D017925:Circovirus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D020869:Gene Expression Profiling; D015967:Gene Expression Regulation, Viral; D049790:Nuclear Export Signals; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013552:Swine; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000939:Epitopes; D049790:Nuclear Export Signals; D011994:Recombinant Proteins; D014764:Viral Proteins
keywords: Epitope; NES; NLS; ORF3 protein; PCV2