Analysis of the entire genomes of fifteen torque teno midi virus variants classifiable into a third group of genus Anellovirus.
ABSTRACT Recently, we identified a novel human virus with a circular DNA genome of 3.2 kb, tentatively designated as torque teno midi virus (TTMDV), with a genomic organization resembling those of torque teno virus (TTV) of 3.8-3.9 kb and torque teno mini virus (TTMV) of 2.8-2.9 kb. To investigate the extent of genomic variability of TTMDV genomes, the full-length sequence was determined for 15 TTMDV isolates obtained from viremic individuals in Japan. The 15 TTMDV isolates comprised 3175-3230 bases and shared 67.0-90.3% identities with each other, and were only 68.4-73.0% identical to the 3 reported TTMDV isolates over the entire genome. TTMDV possessed a genomic organization with four open reading frames (ORF1-ORF4) with characteristic sequence motifs and stem and loop structures with high GC content, similar to TTV and TTMV. The total of 18 TTMDV genomes differed by up to 60.7% from each other in the amino acid sequence of ORF1 (658-677 amino acids), but segregated phylogenetically into the same cluster, which was distantly related to the TTVs and TTMVs. These results indicate that TTMDV with a circular DNA genome of 3.2 kb, has an extremely high degree of genomic variability, and is classifiable into a third group in the genus Anellovirus.
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ABSTRACT: Torque teno viruses (TTVs) are recently discovered DNA viruses, with heterogeneous genomes, highly prevalent in populations worldwide. The species that infect humans are Torque teno virus (TTV), Torque teno midi virus (TTMDV) and Torque teno mini virus (TTMV). High-resolution melting analysis (HRMA) is a sensitive and effective method for genotyping and mutation scanning. Up to now, HRMA has not been utilized for detection of TTVs. The aim of this study was to asses if HRMA is suitable for detecting TTVs variants. DNA was extracted from the blood and saliva of 13 healthy subjects for method optimization. Additionally, saliva samples from 100 healthy individuals were collected for estimating the TTVs' prevalence. Viral DNA was amplified by heminested polymerase chain reaction (PCR). Second round amplicons were used for the HRMA. The samples were analyzed using two fluorescent dyes, SYBR (®) Green I and EvaGreen®. The prevalence values for TTV, TTMDV and TTMV were 71.0, 31.0 and 54.0%, respectively. The three major melting curve patterns corresponding to TTV, TTMDV and TTMV on HRMA can be easily distinguished regardless of kit used. Our results showed that HRMA is a rapid and efficient method of detecting human TTVs.Balkan Journal of Medical Genetics 06/2013; 16(1):55-62. DOI:10.2478/bjmg-2013-0018 · 0.17 Impact Factor
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ABSTRACT: Anelloviruses are a family of small single stranded circular DNA viruses with a vast genetic diversity. Human infections with the prototype anellovirus, torque teno virus (TTV), are ubiquitous and related viruses have been described in a number of other mammalian hosts. Despite over 15 years of investigation, however, there is still little known about the pathogenesis and possible disease associations of anellovirus infections, arising in part due to the lack of a robust cell culture system for viral replication or tractable small animal model. We report the identification of diverse anelloviruses in several species of wild rodents. The viruses are highly prevalent in wood mice (Apodemus sylvaticus) and field voles (Microtus agrestis), detectable at a low frequency in bank voles (Myodes glareolus) but absent from house mice (Mus musculus). The viruses identified have a genomic organisation consistent with other anelloviruses but form two clear phylogenetic groups that are as distinct from each other as from defined genera.Journal of General Virology 04/2014; 95(Pt 7). DOI:10.1099/vir.0.065219-0 · 3.53 Impact Factor
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ABSTRACT: Human torque teno viruses (TTVs) are new, emerging infectious agents, recently assigned to the family Anelloviridae. The first representative of the genus, torque teno virus (TTV), was discovered in 1997, followed by torque teno mini virus (TTMV) in 2000, and torque teno midi virus (TTMDV) in 2007. These viruses are characterized by an extremely high prevalence, with relatively uniform distribution worldwide and a high level of genomic heterogeneity, as well as an apparent pan-tropism at the host level. Although these viruses have a very high prevalence in the general population across the globe, neither their interaction with their hosts nor their direct involvement in the etiology of specific diseases are fully understood. Since their discovery, human anelloviruses, and especially TTV, have been suggested to be associated with various diseases, such as hepatitis, respiratory diseases, cancer, hematological and autoimmune disorders, with few arguments for their direct involvement. Recent studies have started to reveal interactions between TTVs and the host's immune system, leading to new hypotheses for potential pathological mechanisms of these viruses. In this review article, we discuss the most important aspects and current status of human TTVs in order to guide future studies.Archives of Virology 02/2015; 160(4). DOI:10.1007/s00705-015-2363-9 · 2.28 Impact Factor