- 學位論文
泰國蝦白尾病之病理學、病因學和分子生物學之研究
Pathological, Etiological and Molecular Studies on WhiteTail Disease in Macrobrachium rosenbergii
摘要
泰國蝦感染白尾病而造成繁殖場和飼養場嚴重的經濟損失，其死亡率高達50％。白尾病主要是由M. rosenbergii nodavirus ( MrNV )和extra small virus ( XSV )兩種病毒所引起。本研究收集泰國蝦繁殖場及飼養場共64場次進行研究。收集樣本為外出收集及送至本校南區魚病中心之泰國蝦病例，臨床可見體色白濁不透明，尤其是尾部肌肉白濁。以組織病理學觀察MrNV病毒感染蝦隻，可見肌肉變性或壞死及嗜鹼性細胞質內包涵體出現於部分臟器。檢測陽性共4場 ( 4/64；6.3％ )，以肌肉組織出現比率 ( 4/4；100％ )為最多而XSV皆無特徵性的病理學變化。以RT-PCR檢測MrNV，共16場 ( 16/64；25％ )為陽性。以RT-PCR檢測XSV，共33場 ( 33/64；51.6％ )為陽性。RT-PCR產物經核酸定序後以DNAstar軟體進行氨基酸序列及親緣性分析。全部MrNV株並無明顯差異。XSV則依親緣性分析可分為三群 ( Ⅰ、Ⅱ和Ⅲ )，其中第Ⅰ群迄今在NCBI尚未有相同的基因型登入，為國內泰國蝦XSV所獨有之基因序列。為了達到更快速診斷的目的，本研究乃針對本省已發現的泰國蝦病毒性疾病 ( 白點病、傳染性皮下及造血組織壞死病毒、白尾病 )建立單管多引子聚合酶鏈鎖反應診斷技術，並證明其可行性。
並列摘要
White tail disease (WTD) of the giant freshwater prawn caused heavy economic losses in hatcheries and growing farms, with mortalities up to 50%. Two viruses, Both of the Macrobrachium rosenbergii nodavirus (MrNV) and the extra small virus-like particle (XSV) are thought to be the etiological agents of WTD. In this study, we sampled M. rosenbergii from 64 farms including the hatchery and the growing farms. The clinical signs included appearance of whitish muscles, particularly in tail region. Histological features of MrNV infection were the formation of muscular degeneration or necrosis associated with the presence of basophilic cytoplasmic inclusion bodies (4/64; 6.3%) in visceral organs, especially in the muscles (4/4; 100%). There was no pathognomonic lesions in cases of XSV infection. Diagnosis of MrNV and XSV was carried out by RT-PCR respectively and 16 farms showed positive reaction (16/64; 25%) to MrNV, and 33 farms positive to XSV (33/64; 51.6%). Using the DNAstar software to analyze amino acid sequences, there was no obvious change among MrNV strains. As to XSV infections, our isolates could be further divided into 3 clusters (Ⅰto Ⅲ ). Among them, clusterⅠhad no identical sequence deposited in NCBI. In order to establish a rapid diagnosis technique, this study has successfully set up a multiplex PCR for diagnosis of viral diseases found in Macrobrachium rosenbergii in Taiwan.