A novel B-cell epitope of avian infectious bronchitis virus N protein

Viral Immunol. 2010 Apr;23(2):189-99. doi: 10.1089/vim.2009.0094.


This report describes the identification of a novel linear B-cell epitope at the N-terminus of the avian infectious bronchitis virus (IBV) nucleocapsid (N) protein. A monoclonal antibody designated 2D2 was prepared against the IBV N protein, and a series of 23 partially overlapping, tagged fragments of the IBV N gene were expressed. These peptides and five heterogeneous IBV strains were used to identify the epitope recognized by 2D2 using enzyme-linked immunosorbent assay (ELISA) and Western blotting analysis. The linear motif (11)DSPAPIIKLGG(21), located at the N-terminus of the N protein, was identified as the epitope bound by 2D2. ELISA and Western blotting also showed that this epitope was recognized by IBV-positive chicken serum. We propose that this motif is a linear B-cell epitope of N protein, and is the core sequence for reactivity, as demonstrated by binding of 2D2 to the truncated peptides and different IBV strains. Alignment and comparison of the 2D2-defined epitope with other coronavirus sequences showed that the epitope is conserved among avian coronaviruses. The identified epitope might be useful for clinical applications and as a tool for further study of the structure and function of the IBV N protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Viral / immunology
  • Antibody Specificity
  • China
  • Cloning, Molecular
  • Epitope Mapping
  • Epitopes, B-Lymphocyte / genetics
  • Epitopes, B-Lymphocyte / immunology*
  • Female
  • Infectious bronchitis virus / genetics
  • Infectious bronchitis virus / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Nucleocapsid Proteins / genetics
  • Nucleocapsid Proteins / immunology*
  • Sequence Alignment


  • Antibodies, Viral
  • Epitopes, B-Lymphocyte
  • Nucleocapsid Proteins