Liu Baoyuan, Sun Yani, Chen Yiyang, Du Taofeng, Nan Yuchen, Wang Xinjie, Li Huixia, Huang Baicheng, Zhang Gaiping, Zhou En-Min, Zhao Qin
Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, China.
Scientific Observing and Experimental Station of Veterinary Pharmacology and Veterinary Biotechnology, Ministry of Agriculture, Yangling, Shaanxi, China.
BMC Vet Res. 2017 Sep 7;13(1):282. doi: 10.1186/s12917-017-1203-4.
Avian hepatitis E virus (HEV) infection is common in chicken flocks in China, as currently no measures exist to prevent the spread of the disease. In this study, we analyzed the effect of caged versus cage-free housing arrangements on avian HEV transmission. First, 127 serum and 110 clinical fecal samples were collected from 4 chicken flocks including the two arrangements in Shaanxi Province, China and tested for HEV antibodies and/or virus. Concurrently, 36 specific-pathogen-free chickens were divided equally into four experimental living arrangement groups, designated cage-free (Inoculated), caged (Inoculated), cage-free (Negative) and caged (Negative) groups. In caged groups, three cages contained 3 chickens each. Three chickens each from cage-free (Inoculated) and caged (Inoculated) groups (one chicken of each cage) were inoculated by cutaneous ulnar vein with the same dose of avian HEV, respectively. The cage-free (Negative) and caged (Negative) groups served as negative control. Serum and fecal samples were collected at 1 to 7 weeks post-inoculation (wpi) and liver lesions were scored at 7 wpi.
The results of serology showed that the avian HEV infection rate (54.10%) of the cage-free chickens was significantly higher than the one (12.12%) for caged chickens (P < 0.05). Also, the rate of detection of avian HEV RNA in the clinical fecal samples was significantly higher in the cage-free (22.80%, 13/57) than caged birds (5.66%, 3/53). Moreover, under experimental conditions, the infected number of uninoculated cage-free chickens (6) was significantly higher than the one for the uninoculated caged birds (2), as evidenced by seroconversion, fecal virus shedding, viremia and gross and microscopic liver lesions.
These results suggest that reduction of contact with feces as seen in the caged arrangement of housing chickens can reduce avian HEV transmission. This study provides insights for prevention and control of avian HEV infection in chicken flocks.
禽戊型肝炎病毒（HEV）感染在中国鸡群中很常见，目前尚无预防该疾病传播的措施。在本研究中，我们分析了笼养与非笼养模式对禽HEV传播的影响。首先，从中国陕西省的4个鸡群（包括这两种养殖模式）中收集了127份血清样本和110份临床粪便样本，检测其中的HEV抗体和/或病毒。同时，将36只无特定病原体的鸡平均分为四个实验养殖模式组，分别为非笼养（接种组）、笼养（接种组）、非笼养（阴性对照组）和笼养（阴性对照组）。在笼养组中，三个笼子，每个笼子装3只鸡。分别从非笼养（接种组）和笼养（接种组）中各选3只鸡（每个笼子选1只），通过尺侧皮下静脉接种相同剂量的禽HEV。非笼养（阴性对照组）和笼养（阴性对照组）作为阴性对照。在接种后1至7周（wpi）采集血清和粪便样本，并在7 wpi时对肝脏病变进行评分。
血清学结果显示，非笼养鸡的禽HEV感染率（54.10%）显著高于笼养鸡（12.12%）（P < 0.05）。此外，非笼养组临床粪便样本中禽HEV RNA的检出率（22.80%，13/57）显著高于笼养组（5.66%，3/53）。而且，在实验条件下，通过血清转化、粪便病毒排出、病毒血症以及大体和显微镜下肝脏病变证实，未接种的非笼养鸡的感染数量（6只）显著高于未接种的笼养鸡（2只）。
这些结果表明，笼养模式下鸡与粪便的接触减少，可降低禽HEV的传播。本研究为鸡群中禽HEV感染的预防和控制提供了见解。
