Graduate Institute of Microbiology and Public Health, National Chung Hsing University, #250 Kuokuang Road, Taichung 402, Taiwan.
Vaccine. 2011 Jan 17;29(4):660-7. doi: 10.1016/j.vaccine.2010.11.040. Epub 2010 Nov 27.
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.
血凝素（HA）蛋白在禽传染性鼻炎病原体鸡败血支原体的免疫原性和致病性方面发挥着关键作用，但该蛋白不同结构域的结构组织和抗原性仍不清楚。本研究报告了鸡败血支原体 A 群和 C 群血清型菌株 HA 蛋白中存在一个超变区。该超变区大约位于 HA 蛋白的 1100-1600 个残基。该超变区的序列同一性仅为 18.1%，而该区域上下游的序列同一性分别为 83.8%和 97.8%。使用针对鸡败血支原体全细胞抗原的抗血清进行的 Western blot 分析表明，超变区比 HA 蛋白的其他区域具有更强的抗原性。此外，超变区的抗原性具有血清型特异性。用含有超变区的重组蛋白免疫的鸡对同源血清型的鸡败血支原体的攻毒感染具有保护作用（83-100%的保护率）。这些结果表明，含有超变区的重组蛋白可能是开发鸡败血支原体疫苗的有用抗原。
