Recombinant proteins containing the hypervariable region of the haemagglutinin protect chickens against challenge with Avibacterium paragallinarum

• Published in: Vaccine 2011-01, Vol.29 (4), p.660-667
• Main Authors: Wu, Jin-Ru, Wu, Yi-Ru, Shien, Jui-Hung, Hsu, Yuan-Man, Chen, Chih-Feng, Shieh, Happy K, Chang, Poa-Chun
• Format: Article
• Language: English
• Subjects: Allergy and Immunology; Animals; Antibodies, Bacterial - blood; antigens; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; antiserum; Applied microbiology; Avibacterium paragallinarum; Bacterial Vaccines - genetics; Bacterial Vaccines - immunology; Biological and medical sciences; Blotting, Western; Chickens; Deoxyribonucleic acid; DNA; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; E coli; Experiments; Fundamental and applied biological sciences. Psychology; Genes; Haemagglutinin; hemagglutinins; Hemagglutinins - genetics; Hemagglutinins - immunology; immune response; Immunization; Immunogenicity; Microbiology; Molecular Sequence Data; Pasteurellaceae - genetics; Pasteurellaceae - immunology; Pasteurellaceae Infections - mortality; Pasteurellaceae Infections - prevention & control; Pasteurellaceae Infections - veterinary; pathogenicity; Pathogens; Polymorphism, Genetic; Poultry; Poultry Diseases - mortality; Poultry Diseases - prevention & control; Proteins; recombinant proteins; Recombinant Proteins - genetics; Recombinant Proteins - immunology; sequence analysis; Sequence Analysis, DNA; Sequence Homology; serotypes; Studies; Survival Analysis; Vaccine; vaccine development; vaccines; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Vaccines, Synthetic - genetics; Vaccines, Synthetic - immunology; Western blotting
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2010.11.040

The haemagglutinin (HA) protein plays a key role in the immunogenicity and pathogenicity of Avibacterium paragallinarum, but the domain organization and antigenicity exhibited by different domains of this protein remain unknown. This study reports the presence of a hypervariable region in the HA proteins of strains of serovars A and C of A. paragallinarum. This hypervariable region is located approximately at residues 1100–1600 of the HA protein. The sequence identity found in this hypervariable region was only 18.1%, whereas those upstream and downstream of this region were 83.8 and 97.8%, respectively. Western blot analyses using antisera against the whole-cell antigens of A. paragallinarum showed that the hypervariable region was more antigenic than other regions of the HA protein. Moreover, the antigenicity of the hypervariable region was serovar-specific. Chickens immunized with recombinant proteins that contained the hypervariable region were protected (83–100% protection rate) against challenge infection with A. paragallinarum of the homologous serovar. These results suggest that recombinant proteins containing the hypervariable region may be useful antigens for use in the development of a vaccine against A. paragallinarum.