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Updated: May 3, 2026
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Identification of linear B cell epitopes on the leukotoxin protein of Fusobacterium necrophorum
Jiawei Xiao1, Siwen Yu1, Kai Jiang1
1College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, No. 5 Xinyang Road, Sartu District, Daqing, 163319, Heilongjiang Province, China; Ministry of Agriculture and Rural Affairs Key Laboratory of Prevention and Control of Bovine Diseases, No. 5 Xinyang Road, Sartu District, Daqing, 163319, Heilongjiang Province, China.
Objective:
Fusobacterium necrophorum can cause Lemierre's syndrome in humans and a range of illnesses, including foot rot and liver abscesses, in animals. The main virulence factor released by F. necrophorum is leukotoxin, which has been shown to have a strong correlation with the severity of the disease. Leukotoxin is commonly employed as the key antigen in the formulation of subunit vaccines. Therefore, identification of the B-cell epitope of F. necrophorum leukotoxin is necessary.
Methods:
In this research, we utilized lymphocyte hybridoma technology to develop a monoclonal antibody (mAb), 3D7, targeting the F. necrophorum leukotoxin protein. Identification of B-cell epitopes recognized by 3D7 mAb was achieved through Western blot, ELISA and dot blots using leukotoxin-truncated recombinant proteins and peptides, and through SWISS-MODEL homology modeling and PyMOL visualization.
Results:
The 3D7 mAb was identified as belonging to the IgG1 subclass with a κ-chain light chain. It demonstrated reactivity with the natural leukotoxin. The results showed that the 3D7 mAb recognizes a B-cell epitope of the F. necrophorum leukotoxin protein, I2168SSFGVGV2175 (EP-3D7). Sequence comparison analysis showed that EP-3D7 was highly conserved in F. necrophorum strains, but less conserved in other bacteria, indicating the specificity of EP-3D7. EP-3D7 is present on the surface of leukotoxin proteins in a β-folded manner.
Conclusions:
In summary, these results establish EP-3D7 as a conserved antigenic epitope of F. necrophorum leukotoxin. It could be valuable in the development of vaccines and diagnostic reagents for F. necrophorum epitopes.
