Zhao Qin, Syed Shahid Faraz, Zhou En-Min
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China; Scientific Observing and Experimental Station of Veterinary Pharmacology and Veterinary Biotechnology, Ministry of Agriculture, Yangling 712100, Shaanxi, China.
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, China; Scientific Observing and Experimental Station of Veterinary Pharmacology and Veterinary Biotechnology, Ministry of Agriculture, Yangling 712100, Shaanxi, China.
Vet Microbiol. 2015 Oct 22;180(1-2):10-4. doi: 10.1016/j.vetmic.2015.08.016. Epub 2015 Aug 28.
Avian hepatitis E virus (HEV) is the main causative agent of big liver and spleen disease and hepatitis-splenomegaly syndrome in chickens, and is genetically and antigenically related to mammalian HEVs. HEV capsid protein contains immunodominant epitopes and induces a protective humoral immune response. A better understanding of the antigenic composition of this protein is critically important for the development of effective vaccine and sensitive and specific serological assays. To date, six linear antigenic domains (I-VI) have been characterized in avian HEV capsid protein and analyzed for their applications in the serological diagnosis and vaccine design. Domains I and V induce strong immune response in chickens and are common to avian, human, and swine HEVs, indicating that the shared epitopes hampering differential diagnosis of avian HEV infection. Domains III and IV are not immunodominant and elicit a weak immune response. Domain VI, located in the N-terminal region of the capsid protein, can also trigger an intense immune response, but the anti-domain VI antibodies are transient. The protection analysis showed that the truncated capsid protein containing the C-terminal 268 amino acid residues expressed by the bacterial system can provide protective immunity against avian HEV infection in chickens. However, the synthetic peptides incorporating the different linear antigenic domains (I-VI) and epitopes are non-protective. The antigenic composition of avian HEV capsid protein is altogether complex. To develop an effective vaccine and accurate serological diagnostic methods, more conformational antigenic domains or epitopes are to be characterized in detail.
禽戊型肝炎病毒（HEV）是鸡大肝脾病和肝炎-脾肿大综合征的主要病原体，在基因和抗原方面与哺乳动物HEV相关。HEV衣壳蛋白包含免疫显性表位，并诱导保护性体液免疫反应。更好地了解该蛋白的抗原组成对于开发有效的疫苗以及灵敏和特异的血清学检测方法至关重要。迄今为止，已在禽HEV衣壳蛋白中鉴定出六个线性抗原结构域（I-VI），并分析了它们在血清学诊断和疫苗设计中的应用。结构域I和V在鸡中诱导强烈的免疫反应，并且在禽、人及猪HEV中是共有的，这表明这些共享表位妨碍了禽HEV感染的鉴别诊断。结构域III和IV不是免疫显性的，引发的免疫反应较弱。位于衣壳蛋白N端区域的结构域VI也可触发强烈的免疫反应，但抗结构域VI抗体是短暂的。保护性分析表明，由细菌系统表达的包含C端268个氨基酸残基的截短衣壳蛋白可在鸡中提供针对禽HEV感染的保护性免疫。然而，包含不同线性抗原结构域（I-VI）和表位的合成肽没有保护作用。禽HEV衣壳蛋白的抗原组成总体上很复杂。为了开发有效的疫苗和准确的血清学诊断方法，需要更详细地鉴定更多构象性抗原结构域或表位。
