Identification of a Conserved Linear B-Cell Epitope of Streptococcus dysgalactiae GapC Protein by Screening Phage-Displayed Random Peptide Library

Limeng Zhang; Hua Zhang; Ziyao Fan; Xue Zhou; Liquan Yu; Hunan Sun; Zhijun Wu; Yongzhong Yu; Baifen Song; Jinzhu Ma; Chunyu Tong; Xintong Wang; Zhanbo Zhu; Yudong Cui

doi:10.1371/journal.pone.0131221

Identification of a Conserved Linear B-Cell Epitope of Streptococcus dysgalactiae GapC Protein by Screening Phage-Displayed Random Peptide Library

PLoS One. 2015 Jun 29;10(6):e0131221. doi: 10.1371/journal.pone.0131221. eCollection 2015.

Authors

Limeng Zhang¹, Hua Zhang¹, Ziyao Fan¹, Xue Zhou¹, Liquan Yu¹, Hunan Sun¹, Zhijun Wu¹, Yongzhong Yu¹, Baifen Song¹, Jinzhu Ma¹, Chunyu Tong¹, Xintong Wang¹, Zhanbo Zhu², Yudong Cui³

Affiliations

¹ College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing, P. R. China.
² College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing, P. R. China.
³ College of Life Science and Technology, HeiLongJiang BaYi Agricultural University, Daqing, P. R. China; College of Animal Science and Veterinary Medicine, HeiLongJiang BaYi Agricultural University, Daqing, P. R. China.

Abstract

The GapC of Streptococcus dysgalactiae (S. dysgalactiae) is a highly conserved surface protein that can induce protective humoral immune response in animals. However, B-cell epitopes on the S. dysgalactiae GapC have not been well identified. In this study, a monoclonal antibody (mAb5B7) against the GapC1-150 protein was prepared. After passive transfer, mAb5B7 could partially protect mice against S. dysgalactiae infection. Eleven positive phage clones recognized by mAb5B7 were identified by screening phage-displayed random 12-peptide library, most of which matched the consensus motif DTTQGRFD. The motif sequence exactly matches amino acids 48-55 of the S. dysgalactiae GapC protein. In addition, the motif 48DTTQGRFD55 shows high homology among various streptococcus species. Site-directed mutagenic analysis further confirmed that residues D48, T50, Q51, G52 and F54 formed the core motif of 48DTTQGRFD55. This motif was the minimal determinant of the B-cell epitope recognized by the mAb5B7. As expected, epitope-peptide evoked protective immune response against S. dysgalactiae infection in immunized mice. Taken together, this identified conserved B-cell epitope within S. dysgalactiae GapC could provide very valuable insights for vaccine design against S. dysgalactiae infection.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Animals
Antibodies, Monoclonal / immunology
Antigens, Bacterial / chemistry
Antigens, Bacterial / immunology*
Bacterial Proteins / chemistry
Bacterial Proteins / immunology*
Clone Cells
Conserved Sequence*
Electrophoresis, Polyacrylamide Gel
Enzyme-Linked Immunosorbent Assay
Epitopes, B-Lymphocyte / chemistry*
Epitopes, B-Lymphocyte / immunology*
Hydrophobic and Hydrophilic Interactions
Immunity
Immunization
Mice, Inbred BALB C
Molecular Sequence Data
Peptide Library*
Pliability
Recombinant Fusion Proteins / isolation & purification
Sequence Alignment
Streptococcus / metabolism*

Substances

Antibodies, Monoclonal
Antigens, Bacterial
Bacterial Proteins
Epitopes, B-Lymphocyte
GapC protein, Streptococcus
Peptide Library
Recombinant Fusion Proteins

Grants and funding

This work was supported by National “Twelfth Five-Year” Plan for Science & Technology Support (Grant Nos. 2012BAD12B03 and Nos. 2012BA12B05), National Natural Science Foundation of China (NSFC, Grant Nos. 31072120) and Science and Technology Project for Heilongjiang Agricultural Reclamation Administration (HNK11A-08-01-04). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.