Hsiao Kuang-Liang, Wang Li-Yu, Lin Chiung-Ling, Liu Hsin-Fu
Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan.
Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
PLoS One. 2016 Feb 22;11(2):e0149901. doi: 10.1371/journal.pone.0149901. eCollection 2016.
Torque teno virus (TTV) is a single-stranded DNA virus highly prevalent in the world. It has been detected in eastern Taiwan indigenes with a low prevalence of 11% by using N22 region of which known to underestimate TTV prevalence excessively. In order to clarify their realistic epidemiology, we re-analyzed TTV prevalence with UTR region. One hundred and forty serum samples from eastern Taiwanese indigenous population were collected and TTV DNA was detected in 133 (95%) samples. Direct sequencing revealed an extensive mix-infection of different TTV strains within the infected individual. Entire TTV open reading frame 1 was amplified and cloned from a TTV positive individual to distinguish mix-infected strains. Phylogenetic analysis showed eleven isolates were clustered into a monophyletic group that is distinct from all known groups. In addition, another our isolate was clustered with recently described Hebei-1 strain and formed an independent clade. Based on the distribution pattern of pairwise distances, both new clusters were placed at phylogenetic group level, designed as the 6th and 7th phylogenetic group. In present study, we showed a very high prevalence of TTV infection in eastern Taiwan indigenes and indentified new phylogenetic groups from the infected individual. Both intra- and inter-phylogenetic group mix-infections can be found from one healthy person. Our study has further broadened the field of human TTVs and proposed a robust criterion for classification of the major TTV phylogenetic groups.
细小病毒（TTV）是一种在世界范围内高度流行的单链DNA病毒。通过使用已知会过度低估TTV流行率的N22区域，在台湾东部原住民中检测到该病毒，其流行率较低，为11%。为了阐明其实际流行病学情况，我们用非翻译区（UTR）重新分析了TTV的流行率。收集了140份来自台湾东部原住民的血清样本，其中133份（95%）检测到TTV DNA。直接测序显示，在受感染个体中存在不同TTV毒株的广泛混合感染。从一名TTV阳性个体中扩增并克隆了整个TTV开放阅读框1，以区分混合感染的毒株。系统发育分析表明，11个分离株聚为一个单系群，与所有已知群不同。此外，我们的另一个分离株与最近描述的河北-1株聚类，形成一个独立的分支。根据成对距离的分布模式，这两个新的聚类都被置于系统发育组水平，被设计为第6和第7个系统发育组。在本研究中，我们显示台湾东部原住民中TTV感染的流行率非常高，并从受感染个体中鉴定出了新的系统发育组。在一个健康个体中可以发现系统发育组内和组间的混合感染。我们的研究进一步拓宽了人类TTV的领域，并提出了一个强有力的主要TTV系统发育组分类标准。
