新城雞瘟病毒是造成禽類嚴重傳染性呼吸疾病的RNA病毒，而王功強毒株及潮州強毒株均是由已接種疫苗卻仍爆發雞瘟流行的地區所分離出之臺灣新城雞瘟分離株，其中王功強毒株可耐受疫苗用強毒株病毒所產生的抗體之中和作用，且以細胞培養時生長的情形與其他病毒株不同。為了確定王功強毒株及潮州強毒株的基因是否發生變異，本論文比較兩者與參考病毒株，佐藤強毒株、石井強毒株及石井弱毒株，以及與用雞胚纖維母細胞(chicken embryo fibroblast cell；CEF)培養出的王功強毒株(CEF)，這六株病毒株的三個結構蛋白質之基因序列是否有差異。於實驗中將六株病毒株的RNA純化後，利用反轉錄與聚合□連鎖反應(reverse transcription and polymerase chain reaction；RT-PCR)放大欲分析的M、F及HN三個基因片段，並將其分別選殖及定序，再比較分析基因序列以及所預測的基因產物序列。結果顯示，在含有nuclear localization signal (NLS)的M基因片段中，王功強毒株與其他參考病毒株並無明顯差異；但在包含F2/F1切點的F基因片段及所設計放大的HN基因片段中，王功強毒株的兩個基因序列則有顯著的改變，在F基因產物中E104G及另一個蛋白□切點S139A有變異，而HN基因產物中的胃蛋白□切點也有A182T及T257I的改變，因此推斷王功強毒株應與其他參考病毒株不同。此外，結果亦發現佐藤強毒株與潮州強毒株的序列完全相同，而王功強毒株與王功強毒株(CEF)也是序列完全相同，故推論佐藤強毒株與潮州強毒株應是同一株病毒，而以不同方法培養的王功強毒株基因並無明顯差異。

Newcastle disease virus (NDV) is an enveloped RNA virus causing the respiratory system disease of the avian. The isolate Wang-kung of NDV was isolated from an outbreak in Taiwan in 1999, this isolate could escape from the challenge of the antibody produced from the velogenic vaccined NDV isolate. To identify the variant of the new Taiwan NDV isolate, we purified the RNA genome of five different NDV strains, the isolate Wang-kung, Zhao-zhou, and the highly virulent NDV reference strain Sato, Ishii, and the lentogenic NDV strain Ishii. After amplifying the matrix (M), fusion (F), and hemagglutinin- neuraminidase (HN) gene fragments by RT-PCR, the sequences were aligned and analyzed. We found the nuclear localization signal in the M gene fragment products had no significant variant. Besides, the amino acid sequences of the F2/F1 cleavage site in the F gene fragments and the HN gene fragments were much variable between NDV isolate Wang-kung and other reference strains, E104G and S139A in the predicted F gene fragment product, and A182T and T257I in the pepsin cleavage site of the predicted HN gene fragment product. NDV isolate Wang-kung is a new variant in Taiwan and different from the reference strains using for the vaccine of the chickens. NDV isolate Wang-kung from the 10-days chicken embryo and the chicken embryo fibroblast cell are all the same in the nucleotide sequences. The different incubation conditions will not affect the gene sequences of NDV isolate Wang-kung.

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