豬生殖與呼吸綜合症：台灣分離病毒株感染新生仔豬之致病機制

Porcine Reproductive and Respiratory Syndrome Virus Infection: the Pathogenesis of Taiwan MD-001 Strain in Colostrum-deprived Newborn Piglets

李泔泓(Kan-Hung Lee) ； 鄭謙仁(Chian-Ren Jeng) ； 龐飛(Victor Fei Pang) ； 闕玲玲(Ling-Ling Chueh)

《中華民國獸醫學會雜誌》 25卷2期 (1999/06) Pp. 153-160

https://doi.org/10.7009/JTCSVS.199906.0153

摘要

本實驗以原位雜交技衛，探討豬生殖與呼吸綜合症病毒（porcine reproductive and respiratory syndrome virus, PRRSV）台灣分離株MD-001在實驗感染的新生小豬體內的分佈，進而解析此病的致病機制。實驗對象為未吃初乳的二日齡無特定病原PRRSV-free小豬，實驗組小豬以PRRSV由鼻腔接種進行攻毒。所使用的RNA採針係選殖自PRRSV第七開放讀碼區。雜交結果顯示，有陽性細胞存在的組織包括肺、淋巴組織、肝、腎、主動脈、心臟、十二指腸、空腸、骨骼肌、皮膚、睪丸、子宮、腦、腦下垂體、腎上腺及唾液腺。所有淋巴結均於感染後第一天出現較其他組織多的陽性細胞，但其數量隨時間增長而減少。反之，肺臟則於攻毒後第一天僅出現少量的陽性細胞，但其數量隨時間增長而增加。其他組織的陽性細胞則零星出現於攻毒後的第3及7天。依細胞的型態特徵和所在的位置而言，陽性細胞多屬單核性吞噬細胞（mononuclear phagocytic cells）。綜合本實驗的結果，推論新生小豬於感染PRRSV後，病毒先在肺臟的巨噬細胞進行增殖後隨血液清或淋巴液進入體內各淋巴結進行復製，進而導致病毒血症，散播至各組織並以感染單核性吞噬細胞為主，造成多重器官的感染。而由病毒血症的分析結果更進一步發現新生仔豬對PRRSV的感受性甚高，因此PRRSV對新生仔豬的致害亦不容忽視。

關鍵字

豬生殖與呼吸綜合症病毒 ； 台灣分離株 ； 新生仔豬 ； 原位雜交 ； 致病機制

並列摘要

This study used a non-radioactive in situ hybridization technique to determine the distribution and localization of porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected colostrum-deprived specific pathogen free newborn piglets. The infected piglets were inoculated at 2 days old by nasal instillation of local PRRSV isolate MD-001 at a dose of 10^5 TCID(subscript 50). The RNA probe used for in situ hybridization was prepared from a 433 bp cDNA fragment corresponding to the open reading frame 7 of PRRSV genome. Hybridization signals specific for PRRSV RNA were detected in the lung, Iymphoid tissue, liver, kidney, aorta, heart, duodenum, ileum, skeletal muscle, skin, testis, uterus, brain, pituitary gland, adrenal gland, and salivary gland. The most abundant and consistent positive signal was observed in Iymph nodes, particularly at 1 day post-infection (DPI); thereafter, the number of positive cells decreased. In the lung, although a few positive cells were found at 1 DPI, the number increased with time. Only scattered positive cells were found in other tissues. Results in this study indicate that newborn piglets are highly susceptibile to PRRSV infection. The infection is characterized by initial viral replication in the lung or Iymph nodes followed by viremia with subsequent distribution to multiple organs.

並列關鍵字

Porcine reproductive and respiratory syndrome virus ； Taiwan isolate ； Colostrum-deprived SPF piglets ； Insitu hybridization ； Pathogenesis