台灣克沙奇病毒 B1 分子流行病學研究

Molecular epidemiology of Coxsackievirus B1 in Taiwan

陳昱憲(Yu-Hsien Chen)

指導教授 ： 褚佩瑜

高雄醫學大學/健康科學院/醫學檢驗生物技術學研究所/碩士(2012年)

摘要

克沙奇病毒B1 (Coxsackievirus B1, CV-B1)在台灣是一幾乎每年都能分離到的散發型感染腸病毒，因腸病毒的種內與種間的基因重組是很常見的現象，散發型的感染常為人所忽略，而常在腸病毒可提供一個種內與種間重組的供應者。為了瞭解常在的散發型腸病毒基因重組情形，我們交叉比對分析於南台灣分離的22株 (1989-2010)與來自基因庫CV-B1之外殼蛋白VP1 (276 nt，87株) 及聚合酶3D (414 nt，35株) 的核苷酸序列，並以CVB2-6原型株為外群。以Neighbor-Joining (NJ)、Maximum Likelihood (ML)、MrBayes與BEAST Markov Chain Monte Carol (BMCMC ) 方法作演化分析樹，四種分析結果得到相同的拓樸構形，根據VP1基因結果顯示CV-B1病毒與CVB2-6原型株分離自成一個大分枝此分枝的支持度在NJ與ML 的bootstrap（BS）都>70%且在MrBayes與BMCMC的posterior probability (PP) > 0.90。CV-B1可再區分為三大基因群，Genotype I-III (GI-GIII)，GI出現在美洲和羅馬尼亞 (1974-1982)；GII出現於韓國、日本、中國及台灣 (1993-2010)年;GIII (2002-2010)美國、亞洲、歐洲等地，且都根據地域群聚成小分枝傾向。比對VP1基因與3D基因的種系分析結果顯示雖兩者都分為三個亞群，但CV-B1病毒株無法根據血清型自成一個分枝，CV-B3的原型株與CV-B1一株AY37320 自成一個小分枝1 (BS>73%、PP >0.95）。值得注意的是VP1中原本屬於GII、GIII的部分病毒株也在3D中發生互相置換的情形，尤其是VP1 的GIII中11株的台灣分離株有四株被分到 3D樹的GII群，而2株在被分到 3D樹的GIII群。這根據不同基因片段的演化樹分析得不相符合的基因群分類的結果，甚至到3D基因分群與血清型分群不相符合的結果，意味著這經年常在的散發型病毒CV-B1不僅可能彼此發生重組，也有可能與其他腸病毒發生重組。因為新出現的突變株常是導致腸病毒大流行的主要原因，因此監控經年常在的散發型病毒在分子流行病學也是重要的課題。

關鍵字

克沙奇病毒B1 ； 分子流行病學

並列摘要

In Taiwan, Coxsackievirus B1 (CV-B1) has been isolated almost annually since 1989. Since interserotypic genetic recombination is very common in enterovirus, this study characterized interserotypic genetic recombination in sporadic enterovirus isolates. The VP1 (276 nt, 87 strains) and polymerase 3D (414 nt, 36 strains) nucleotide sequences of twenty-two Taiwan isolates of CV-B1 (1989-2010) were compared with those of other CV-B1 strains isolated worldwide and with those of the CVB2-6 prototype strains as the outgroup. Phylogenetic analyses were performed by Neighbor-Joining, Maximum Likelihood, and Markov Chain Monte Carlo methods. All methods consistently showed the same topology, and each of three genotypes (designated GI-GIII) were identified in the VP1 and 3D regions. The VP1 tree showed a branch support by bootstrap (BS) or posterior probability (PP) > 70%. The CV-B1 can be clustered into three genetic groups, Genotype I (GI) in the Americas and Taiwan (1948-1989); Genotype II (GII), which appeared in 1971, and Genotype III (GIII), which appeared in 1989. The GII and GIII strains, which have co-circulated until recently, have been isolated in the United States, Asia, Europe and elsewhere and tend to be clustered in the same geographic regions. Unlike the VP1 tree, however, the 3D tree showed that the strains did not tend to cluster by serotype. For example, the CV-B3 prototype strain was clustered together with a CV-B1 strain (AY 37320) with a significant branch support (BS or pp >73%). Intergenotypic inconsistencies between the VP1 and 3D trees were also noted. The positions of the GII strains, and particularly the positions of the GIII strains, in the VP1 tree were reversed in the 3D tree. For example, in the VP1 tree, eleven Taiwan isolates were clustered in the GIII strain, and four were clustered in the GI strain. In the 3D tree, however, two Taiwan isolates were clustered in the GII strain. The incongruencies in the VP1 and 3D tree topologies in terms of serotype and genotype clustering showed that the circulating CV-B1 had recombined not only with itself, but also with other enteroviruses. Because the new mutant is often the main cause of an enterovirus epidemic, continuous molecular epidemiological studies of sporadic viruses are essential for effective enterovirus surveillance.

並列關鍵字

Coxsackievirus B1 ； Molecular epidemiology

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