探討E型肝炎病毒在豬隻、動物園野生動物及環境中野鼠的感染狀態

Detection of Hepatitis E virus (HEV) Infection in Farm Pigs, Zoo Animals and Environmental Rodents in Taiwan

陳珮菁(Pei-Ching Chen)

指導教授 ： 鄭謙仁

共同指導教授 ： 龐飛(Victor Fei Pang)

國立臺灣大學/生物資源暨農學院/獸醫學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01927

摘要

E型肝炎病毒 (Hepatitis E virus；HEV) 是經糞口途徑傳播，為許多發展中國家和工業化國家非A及非B型肝炎中的主要病因。美國及日本可在豬隻及野生動物身上發現HEV感染的病例，因此HEV在台灣地區可能也是一個重要的人畜共通疾病。因此本研究針對豬隻、動物園動物及環境野鼠進行HEV檢測。本研究收集2006年至2007年台灣南部地區病死或病弱豬隻196例，以RT nested- PCR檢測其HEV陽性率為7.65% (15/196)，在不同的檢測樣本中，以糞便樣本檢出率較高，為10.00% (7/70)，肝臟樣本陽性率為5.22% (7/134)，膽汁樣本陽性率為2.11% (2/95)。若以感染豬隻年齡進行分析，主要以4至9週齡豬隻的陽性比例較高，約為9.65% (11/114)，0至4週齡陽性比例為4.26% (2/47)，9至16週齡陽性比例為6.67% (2/30)，至於在16週齡以上豬隻的陽性比例為0% (0/5)。將陽性PCR產物經核苷酸定序，並與5株台灣HEV分離株的基因序列比對結果，其相似性達80.8%∼93.7%，與其他國家HEV genotype 4相似性達84.0%~88.9%，與genotype 2及genotype 3的序列相似性分別為66.6%∼68.6%及71.8%∼76.3%。本研究之動物園動物及野鼠肝臟樣本均無陽性病例檢出 (0/144 及0/12)。利用原位雜交法 (In-situ hybridization；ISH) 和免疫組織化學染色 (Immunohistochemistry；IHC) 偵測HEV核酸及抗原分佈位置，在肝細胞及庫氏細胞 (Kupffer cells) 之細胞質內可見陽性訊號，IHC可在膽管上皮細胞表面發現陽性訊號。本實驗結果顯示台灣豬隻已經有HEV感染病例出現，其中又以4至9週齡豬隻的陽性比例較高，另外，核酸序列分析結果也證實台灣HEV應屬於一種本土特異株。

關鍵字

E型肝炎病毒

並列摘要

Hepatitis E virus (HEV) is the major cause of enterically transmitted non-A, non-B hepatitis in many developing countries and is also endemic in many industrialized countries. The recent discovery of HEV in domestic pigs and wild animals in United States and Japan, respectively, has suggested that HEV may be an important zoonotic issue in Taiwan. Thus, the aim of this study was to investigate HEV infection in farm pigs, zoo animals and environmental rodents in Taiwan. Between 2006 and 2007, we collected 17 serum samples, 136 liver samples, 102 bile samples and 104 fecal samples from pig farms; 13 liver samples of primates, 52 mammals' liver samples, 45 reptiles' liver samples and 34 avian liver samples from Taipei city zoo and 14 liver samples from environmental rodents. HEV RNA was detected by reverse transcriptase nested polymerase chain reaction (RT nested-PCR) from homogenates of the samples. HEV positive signals were detected in 7 of 134 (5.22%) liver samples, 2 of 95 (2.11%) bile samples and 7 of 70 (10.00%) fecal samples from pig farms. The porcine serum samples and all liver samples from zoo animal and environmental rodent were all negative. The highest HEV positive rate (9.65%) was in pigs of 4 to 9 weeks age, followed by 6.67% and 4.26% in pigs of 9 to 16 weeks and 0 to 4 weeks age, respectively; and none in pigs older than 16 weeks age. The identity of nucleotide sequences of PCR products was 80.8%∼93.7% between swine and human HEV strains in Taiwan, 84.0%~88.9% between genotype 4 strains from different countries, and 66.6%∼68.6% and 71.8%∼76.3% between genotype 2 and genotype 3 strains. By in-situ hybridization (ISH) and immunohistochemistry (IHC), the positive signals were detected in cytoplasm of hepatocytes and kupffer cells. In addition, the positive signals were also detected on the luminal surface of bile epithelial cells by IHC. The HEV infections of pigs in Taiwan are confirmed in this study. The most susceptible age is from 4 to 9 weeks old. Besides, the result of sequence analysis also supports that HEV of Taiwan isolated belongs to an unique local or regional strain.

並列關鍵字

Hepatitis E virus

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