Effect of age on the pathogenesis of duck tembusu virus in Cherry Valley ducks.
Effect of age on the pathogenesis of duck tembusu virus in Cherry Valley ducks.
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DOI：
10.3389/fmicb.2015.00581
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发表时间：
2015
影响因子：
5.2
通讯作者：
Liu S
中科院分区：
文献类型：
--
作者：
Li N;Lv C;Yue R;Shi Y;Wei L;Chai T;Liu S
在鸭身上研究了宿主年龄对鸭坦布苏病毒（DTMUV）感染结果的影响。对1、3、7周龄的三组樱桃谷鸭进行DTMUV肌肉注射，系统观察其临床症状、病理变化、组织病毒载量和免疫反应。早在感染后 2 天（dpi），1 周龄的鸭子就出现了严重的临床症状和神经功能障碍，有些鸭子在 5-7 dpi 时死亡。三周大的鸭子表现出类似但较轻微的症状，并且没有死亡。然而，7周大的鸭子仅表现出短暂的食欲不振。随着鸭子的成熟，肉眼病变的严重程度逐渐减轻。 1周龄鸭心内膜出血，脾肿大，回肠淋巴滤泡肿胀，肝、肾肿胀变性，脑膜充血。三周龄的鸭只表现出轻微的病理损伤。在 7 周龄的鸭子中没有观察到可见的损伤。然而，病理组织学分析表明所有受感染的鸭子均表现出病毒性脑炎。 1周龄鸭脑部早在1 dpi就可以检测到DTMUV，且3~5 dpi时1周龄鸭大部分器官的病毒滴度显着高于3周龄和7周龄鸭。 IFN-γ、IL-2及血清中和抗体的变化规律相似，感染早期幼龄鸭与年老鸭之间差异有显着性（P < 0.05）。更重要的是，虽然所有感染鸭子的抗体滴度在 9 至 17 dpi 期间相似，但与其他两组相比，在最年轻的组中观察到病毒清除率降低，这表明免疫系统成熟度比中和抗体的存在更重要。总之，本研究表明，病毒发病机制在 1 周龄鸭中最强，且与年龄相关的免疫反应在鸭 DTMUV 发病机制中发挥着重要作用。
The effect of host age on the outcome of duck tembusu virus (DTMUV) infection was studied in ducks. Three groups of Cherry Valley ducks at 1, 3, and 7 weeks of age were intramuscularly infected with DTMUV to systematically observe the clinical symptoms, pathological changes, tissue viral loads, and immune responses. Severe clinical symptoms and neurological dysfunction were observed in 1-week-old ducks as early as 2 days post infection (dpi) and some died at 5–7 dpi. Three weeks-old ducks showed similar but milder symptoms and no deaths. However, 7-weeks-old ducks showed only transient loss of appetite. Gross lesions gradually reduced in severity as ducks matured. One-week-old ducks showed endocardial hemorrhage, splenomegaly, swelling in the lymph follicles of the ileum, liver, and kidney swelling with degeneration, and meningeal hyperemia. Three-weeks-old ducks showed only mild pathological lesions. No visible lesions were observed in 7-weeks-old ducks. However, pathological histology analysis demonstrated all infected ducks displayed viral encephalitis. DTMUV could be detected in the brains of 1-week-old ducks as early as 1 dpi and virus titers of most organs in 1-week-old ducks were significantly higher than that of 3- and 7-weeks-old ducks at 3–5 dpi. The patterns of IFN-γ, IL-2, and serum neutralizing antibodies were similar, and there were significant difference between the youngest ducks and the older ducks at early infection stage (P < 0.05). More important is that although the antibody titers of all infected ducks were similar from 9 to 17 dpi, reduced clearance of virus was observed in the youngest groups comparing with the other two groups, indicating that immune system maturity was more important than the presence of neutralizing antibody. In summary, this study demonstrates that viral pathogenesis is strongest in 1-week-old ducks and the age-related immune response plays an important role in the pathogenesis of DTMUV in ducks.