鸭瘟病毒对SPF鸭的致病性研究

【目的】探讨鸭瘟病毒（Duck plague virus，DPV）对SPF鸭的致病性。【方法】将DPV分别通过点眼滴鼻和皮下注射接种途径人工感染SPF鸭，以未攻毒健康SPF鸭为对照，观察各组鸭的发病情况及症状，于感染后不同时间随机剖杀试验组和对照组SPF鸭，采集肝脏、脾脏、肾脏、肺、心脏、气管、食道、肠道、胸腺、法氏囊、脑和泄殖腔等组织，常规方法制备石蜡切片，HE染色，观察各器官病理组织学变化，同时利用间接免疫荧光染色法（IFA）对DPV抗原在鸭体内的分布进行检测，并进行血常规和血液生化指标检测，分析了DPV对SPF鸭淋巴细胞转化率的影响。【结果】DPV接种后，引起鸭高热、下痢，组织器官出血、坏死，食道、泄殖腔黏膜出血、溃疡并有灰黄色假膜覆盖；病理组织学变化以血管壁损伤为主，肝、脾细胞变性、坏死，消化道黏膜上皮细胞坏死脱落。DPV感染后，在鸭的脾脏、胸腺、法氏囊、肝脏、食道、泄殖腔、肠道、肾脏、肺及气管中均检测到DPV抗原，且以肝脏、脾脏等组织中荧光最强；在脑和心脏中均未检测到DPV抗原。DPV感染组鸭血清中白细胞总数（WBC）、红细胞总数（RBC）、血小板总数（PLT）和总蛋白（TP）、血红蛋白（HGB）含量及丙氨酸氨基转移酶（ALT）、碱性磷酸酶（ALP）、天门冬氨酸氨基转移酶（AST）活性、淋巴细胞转化率与对照组差异大多达显著或极显著水平。【结论】DPV感染主要引起SPF鸭各组织器官广泛性出血；脾脏、胸腺、法氏囊等免疫器官首先受到攻击和损害，并造成免疫抑制；皮下注射接种DPV比点眼滴鼻接种对SPF鸭的致病性强。

Study on pathogenicity on SPF ducks of duck plague virus

【Objective】 The experiment was made to study the pathogenicity of duck plague virus on SPF ducks.【Method】 The SPF ducks were artificially infected DPV through the intraocular-nasal vaccination and subcutaneous injection challenge.Another group of the SPF ducks unartificially infected with DPV was negative control group.The incidence and clinical symptoms of ducks were observed.The ducks of experimental group and the negative control group were killed randomly after infection at different times.The tissues and organs,including liver,spleen,renal,lung,heart,trachea,esophagus,intestinal,thymus,bursa,brain and cloaca,were sliced into the paraffin sections and stained by conventional HE staining.While the histopathological changes of these organs were observed,the distribution of DPV in duck’s tissues was studied with IFA(indirect fluorescent antibody test).Their blood was collected to carry out the blood routine and the blood biochemical tests,and the impacts of DPV on lymphocyte transformation of duck were investigated.【Result】 Fever and diarrhea resulted in the SPF ducks by being inoculated with DPV.Tissues and organs were hemorrhage and necrosis.Esophageal and cloacal mucosa covered with yellowish green pseudomembrane were hemorrhage and ulcerative.Histopathological changes were characterized by the damage of vessel walls.Cells of liver and spleen were denature and necrosis.And submucosal epidermal cells were necrosis and shed.The IFA was applied in detecting the virulent DPV antigen in different organs of the artificially infected adult ducks,and the viral antigen was detected in the spleen,thymus,bursa,liver,esophagus,duodenal,renal,lung and trachea of infected ducks.And the fluorescent of liver and spleen was the strongest.But DPV was not detected in brain and heart.The content of HGB,WBC,RBC,ALT,ALP,AST and TP of infected ducks’ serum significantly or very significantly changed.The lymphocyte transformation of experimental group was different compared with control group.【Conclusion】 After infected with DPV,the extensive hemorrhage of tissues was found.Immune organs,such as spleen,thymus and bursa,were attacked and damaged firstly.The subcutaneous injection had stronger pathogenicity on SPF ducks than intraocular-nasal vaccination vaccination.