| Summary: | 碩士 === 國立屏東科技大學 === 獸醫學系所 === 96 === 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.
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