New Phylogenetic Groups of Torque Teno Virus Identified in Eastern Taiwan Indigenes.

Kuang-Liang Hsiao,Chiung-Ling Lin,Hsin-Fu Liu,Li-Yu Wang,Patrick Cy Woo

doi:10.1371/journal.pone.0149901

Abstract

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.

Highlights

During the search for possible pathogens of non-A to E hepatitis, a novel DNA virus was discovered and named TT virus after the initials of the index patient [1]
Putative ORF1 is the longest ORF of Torque teno virus (TTV) which covering around two-thirds of entire viral genome
Our result showed the TTV prevalence was underestimated in previous study that used N22 region for PCR detection [10]

Summary

Introduction

During the search for possible pathogens of non-A to E hepatitis, a novel DNA virus was discovered and named TT virus after the initials of the index patient [1]. To determine the phylogenetic relationship of eastern Taiwanese indigenous strains among human TTV, a total of 160 TTV ORF1 sequences from GenBank and 13 isolates from this study (S1 Appendix) were included for phylogenetic analysis. TTV DNA prevalence was estimated 95% (133/140) in healthy individuals of eastern Taiwanese indigenes by detecting UTR region.

Results

Conclusion