Syed Shahid Faraz, Sun Yani, Du Taofeng, Chen Yiyang, Liu Baoyuan, Wang Xinjie, Li Huixia, Nan Yuchen, Zhou En-Min, Zhao Qin
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, PR China; Scientific Observing and Experimental Station of Veterinary Pharmacology and Diagnosis, China Ministry of Agriculture, Yangling 712100, Shaanxi, PR China; Faculty of Veterinary and Animal Sciences, Lasbella University of Agriculture, Water and Marine Sciences, Uthal, Baluchistan, Pakistan.
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, PR China; Scientific Observing and Experimental Station of Veterinary Pharmacology and Diagnosis, China Ministry of Agriculture, Yangling 712100, Shaanxi, PR China.
Vaccine. 2017 Jun 14;35(27):3482-3489. doi: 10.1016/j.vaccine.2017.05.030. Epub 2017 May 18.
Avian hepatitis E virus (HEV) is the etiologic agent of big liver and spleen disease in chickens. In 2010, the Chinese avian HEV (CaHEV) strain was isolated from chickens and demonstrated to cause the decreased egg production in layer hens. No avian HEV commercial vaccine has yet been developed to prevent virus infection in China. In this study, recombinant CaHEV truncated ORF2 and complete ORF3 proteins were evaluated separately for immunoprotection of chickens against CaHEV infection. First, truncated ORF2 and complete ORF3 proteins were expressed in Escherichia coli. Next, 48 specific-pathogen-free chickens were randomly divided into three groups. One group was immunized with truncated ORF2 protein, the second group was immunized with recombinant ORF3 protein, while the third group (control) was mock-immunized with PBS. After booster immunization, chickens in all three groups were challenged intravenously with CaHEV infectious stock and assessed for viremia, fecal virus shedding, seroconversion, and gross hepatic lesions. In the ORF2 protein-immunized group, no chickens showed evidence of avian HEV infection. In the ORF3 protein-immunized group, nine chickens exhibited viremia and seven had fecal virus shedding. In the control group, all 16 chickens showed viremia and fecal virus shedding. However, the durations in chickens from the ORF3 protein group (2-4weeks) were shorter than the ones from the control group (4-8weeks). Moreover, no gross liver lesions emerged in the ORF2 protein group, while lesions observed in the ORF3 protein group were milder than in controls. Therefore, the ORF2 protein can confer complete immunoprotection against chicken CaHEV infection, while the ORF3 protein only confers partial immunoprotection.
禽戊型肝炎病毒（HEV）是鸡大肝脾病的病原体。2010年，从鸡中分离出中国禽HEV（CaHEV）毒株，并证明其可导致蛋鸡产蛋量下降。在中国，尚未开发出禽HEV商业疫苗来预防病毒感染。在本研究中，分别评估了重组CaHEV截短的ORF2和完整的ORF3蛋白对鸡抵抗CaHEV感染的免疫保护作用。首先，截短的ORF2和完整的ORF3蛋白在大肠杆菌中表达。接下来，将48只无特定病原体的鸡随机分为三组。一组用截短的ORF2蛋白免疫，第二组用重组ORF3蛋白免疫，而第三组（对照组）用PBS进行模拟免疫。加强免疫后，对所有三组鸡静脉注射CaHEV感染性原液进行攻毒，并评估病毒血症、粪便病毒排出、血清转化和肝脏大体病变。在ORF2蛋白免疫组中，没有鸡表现出禽HEV感染的迹象。在ORF3蛋白免疫组中，9只鸡出现病毒血症，7只鸡粪便中有病毒排出。在对照组中，所有16只鸡都出现了病毒血症和粪便病毒排出。然而，ORF3蛋白组鸡的病毒血症和粪便病毒排出持续时间（2 - 4周）比对照组（4 - 8周）短。此外，ORF2蛋白组没有出现肝脏大体病变，而ORF3蛋白组观察到的病变比对照组轻。因此，ORF2蛋白可提供针对鸡CaHEV感染的完全免疫保护，而ORF3蛋白仅提供部分免疫保护。
