猪繁殖与呼吸综合征病毒SJ株(天津分离株)感染仔猪的病理学

Pathological Changes in Piglets Infected with SJ Strain of PRRSV

选用10~15日龄健康仔猪20头,随机分为攻毒组(15头)与对照组(5头),攻毒组滴鼻接种猪繁殖与呼吸综合征病毒(PRRSV)SJ株,3 mL/头;对照组滴鼻接种无PRRSV的细胞培养物,3 mL/头。攻毒组的主要临床表现为眼睑水肿、打喷嚏、呼吸急促、嗜睡、体温略升高。攻毒组与对照组在试验开始后24 h、7 d、14 d、21 d、28 d分别剖杀3头和1头仔猪,采集肺、脾、肾、扁桃体及各部位淋巴结作免疫组化及病理组织学观察;迅速采集肺组织,制作超薄切片,透射电镜观察。试验结果表明,PRRSV SJ株主要感染仔猪的肺脏与脾脏。免疫组化观察,攻毒后24 h^7 d,肺门淋巴结和扁桃体PRRSV抗原阳性反应最强;攻毒后14~28 d,脾脏PRRSV抗原阳性反应最强。攻毒后14~28 d,显微病变可见肺组织发生弥漫性、局灶性或间质性肺炎,肺泡隔因巨噬细胞、淋巴细胞及Ⅱ型上皮细胞增生而明显增厚。超微病变主要表现为,肺泡间隔中单核细胞增生,核孔消失,核内有异染色质聚集,Ⅱ型肺泡细胞高度变性等。

Twenty 10 15-day-old healthy piglets were divided randomly into challenge Group（15 piglets） and control group （ 5 piglets）. SJ strain of PRRSV（3 mL/head） was inoculated intranasally in challenge group and cell culture medium of non PRRSV（3 mL/head） was inoculated in control group. Three piglets（in challenge group） and one piglet（in control group） were killed individually in 24 h,7 d,14 d,21 d,28 d after starting experiment. Their lung,spleen,kidney,tonsil and lymphonodes in different organs were collected and used for immunohistochemical and histological study. The lungs of the challenge and control groups were collected immediately and used for uhrastructural observation. The results of immunohistochemistry indicated that the most intense and widespread PRRSV positive cells in bronchopulmonary lymph nodes and tonsil were at 24 h-7 d postinoculation. The same result in spleen was at 14-28 d postinoculation. The histological lesions of PRRSV infected piglets were characterized by infiltration of macrophages and lymphocytes in alveolar septum, peribronchial lymphoid hyperplasia in the peribronchial area and interstitial pneumonia. Uhrastructurally,abnormal morphological nucleus and disappeared nucleohole were found in the hyperplastic monocytes in the alveolar septum. The type Ⅱ alveolar cells were severe degeneration and the membrane of rough endoplasmic reticulum were broken.