高致病性猪蓝耳病自然病例与美洲株(VR-2332)人工感染猪的比较病理学

Comparative pathology of piglets natually infected with high-pathogenic PRRSV and artificially infected with American strain PRRSV(VR-2332)

为了解猪繁殖与呼吸综合征病毒(PRRSV)美洲株与我国当今流行的高致病性毒株在致病性上的差异,对高致病性PRRSV自然感染病例和美洲株VR-2332人工感染猪进行比较病理学研究,探讨PRRSV高致病性毒株的致病特点及发病机制。结果显示,高致病性PRRSV会引起发病猪耳和四肢末端迅速发绀、皮肤点状出血、急性肺实变、全身出血性坏死性淋巴结炎、急性炎性脾肿、部分病例脾边缘出血性梗死灶、肾点状出血和胃肠黏膜出血等剖检病变,死亡病猪具有急性出血性败血症的剖检病变特征。全身性淋巴组织急性坏死、重度病毒性脑炎、实质器官变性坏死及肺继发感染为高致病性PRRSV自然感染病例的组织病变特征,这是导致病猪急性死亡和多继发感染的的主要原因。两病毒感染猪的肺和扁桃体免疫组化染色阳性细胞以及肺和脾电镜下病毒颗粒的分布、形态基本相同。

In order to find the different pathogenic traits of high-pathogenic PRRSV prevailing in China and American strain PRRSV （VR-2332）, the pathological characters and pathogenesis of piglets naturally infected with high-pathogenic PRRSV and artificially infected by American strain （VR-2332） were studied. The results indicated that the typical pathological changes of piglets naturally infected with high-pathogenic PRRSV included quick cyanosis of tips of feet and ears, flecked bleeding in skin, acute consolidation of lung, bleeding necrotic lymphadenitis, acute splenitis,hemorrhagic infarct in the border of spleen, flecked bleeding in kidney as well as gastrointestinal mucous membrane hemorrhage and ulcerations. Dead pigs showed typical changes of acute hemorrhagic septicemia. Acute necrosis of lymphoid tissues,acute viral encephalitis,degeneration and necrosis of parenchymal organs were common tissue pathological change in natural cases, which are main reasons for the death of pigs and secondary infection. The distribution and the appearance of the two kinds of virus particle under electron microscope were the same in lung and spleen as well as positive cells detected by immunohistochemistry in lung,and tonsil.