Establishment of experimental infection model of duck hemorrhagic ovaritis | 鸭出血性卵巢炎实验感染模型的建立

中国人. 目的建立鸭出血性卵巢炎的实验动物感染模型并对其发病特点进行观察，为疫苗研究和筛选评价抗病毒药物提供工具。方法以每只约104个ELD50的剂量经滴鼻、点眼和口服途径感染196日龄北京鸭后，观察鸭临床症状，于感染后5、7、9、21、28、34 d采血和剖检鸭，应用固定病毒稀释血清的方法测定血清中和抗体，取卵泡膜、肝脏、脾脏和脑组织进行病毒分离，对主要组织脏器进行病理学检查。结果攻毒后3、4、5d采食量均显著下降（下降80%），6d采食量恢复至约正常量的50%，11d恢复到正常水平；攻毒后3、4、5d产蛋量出现明显下降，6、7、8d鸭群未见产蛋，36d发病鸭群的产蛋率恢复到60%，39d鸭群的产蛋率达到80%。攻毒后5d 3只（3/3）鸭的卵泡膜和肝脏均可以分离到病毒，7d 2只（2/2）鸭的卵泡膜中均分离到病毒，1只鸭（1/2）脾脏和脑组织中均分离到病毒，9d 1只鸭（1/2）的卵泡膜中分离到病毒，21d和28d卵泡膜病毒分离结果均为阴性。感染鸭的卵巢变性、变形，卵泡膜充血、出血；卵巢、肝脏、脑、脾等组织和脏器均出现以网状细胞（巨噬细胞）增生为主的病理变化，表现为急性出血性卵巢炎、间质性肝炎、非化脓性脑炎、坏死性脾炎、间质性肾炎和轻度的心肌炎。感染后3周可检测出低效价的中和抗体。结论实验感染鸭出血性卵巢炎病毒后可引起急性出血性卵巢炎，利用产蛋北京鸭建立的鸭出血性卵巢炎模型，可用于评价抗病毒药物和疫苗的研究。

英语. Objective The objective of the study is to create an experimental infection model of Duck Hemorrhagic Ovaritis, study the disease characterization and provide an available model for developing vaccine and evaluating antiviral medicine.Method The infected 196-day-old ducks were inoculated with 104 ELD50 of a DHOV isolate, DHOV-HB-F4, via a combination of intranasal, intraoral and intraocular inoculation method. Clinical signs were observed and recorded daily. At 5, 7, 9, 21, 28 and 34 day after inoculation, serum samples were taken, randomly selected and sacrificed for necropsy. Gross lesions were recorded and various tissues were collected for histological examination. Various tissues including ovaries, liver, brain, and spleen were collected for re-isolating virus. The method of fixed virus and diluted sera was used to detect the neutralizing antibody.ResultThe food consumption of infected ducks showed significant decrease (decreased by 80%) at 3, 4, 5 day post inoculation (DPI), recovered to 50% of normal intake at 6 DPI and to normal level at 11DPI. The egg production of infected ducks was significantly decreased at 3, 4, 5 DPI and zero at 6, 7, 8 DPI. The laying rate of infected ducks recovered to 60% of normal at 36 DPI and 80% at 39 DPI. DHO virus could be successfully re-isolated from three ducks’ ovaries and liver on 5 DPI (3/3), two ducks’ ovaries (2/2) and one duck’s spleen and brain(1/2) on 7 DPI, one duck’s ovaries(1/2) on 9 DPI. At 21 and 28 DPI, DHO virus could not be re-isolated from the infected ducks’ tissues. The infected ducks showed ovary degeneration and deformation, follicle membrane hyperaemia and haemorrhagia; ovary, liver, brain and spleen characterized by the reticular cells hyperplasia which showed acute Hemorrhagic Ovaritis, interstitial hepatitis, nonpurulent meningoencephalitis, necrotizing splenitis, interstitial nephritis and mild myocarditis. The infected ducks only produced lower-titer neutralizing antibody on week 3 post inoculation.ConclusionThe experimental ducks showed acute Hemorrhagic Ovaritis after infected by Duck Hemorrhagic Ovaritis. The experimental infection model of Duck Hemorrhagic Ovaritis was developed in Peking duck which could be a model for screening and evaluating the antiviral medicine and vaccine.