Isolation of Multiple TT Virus Genotypes from Spleen Biopsy Tissue from a Hodgkin's Disease Patient: Genome Reorganization and Diversity in the Hypervariable Region

Abstract

We report the isolation of 24 novel genotypes of TT viruses from a surgically removed spleen of a patient with Hodgkin's disease. The sequence analysis of our 24 isolates revealed the remarkable heterogeneity of TT virus isolates not only from the same patient but also from the same biopsy material. These isolates belong to four phylogenetic groups of TT viruses. Nucleotide sequence analyses revealed five distinct genotypes (tth3, tth4, tth5, tth6, and tth7). The limited variation in sequence identity of the other isolates defines the latter as variants of four of these genotypes. A group of 6 isolates (the tth7 group) revealed a reorganization of open reading frame 1 (ORF1) leading to one larger and a varying number of smaller ORFs. The nucleotide difference of the full-length genomes was less than 1%. A variation of 69 to 97% in amino acids of a second group of 8 isolates (the tth3 group) was restricted to the hypervariable region of ORF1, indicating the existence of a quasi-species. These isolates differed by less than 2% in the remainder of their nucleotide sequences. An alignment of these isolates with 79 previously reported TT virus genotypes permits the proposal of TT virus genera and species within the family Anelloviridae in analogy to a previous proposal for the papillomaviruses (family Papillomaviridae).TT viruses (TTV) are ubiquitous in nature and have been demonstrated in more than 90% of serum samples from healthy individuals where they persist over time (14,16,27,41). Viral particles have been purified from feces (17, 34) and, in addition, are excreted in saliva, breast milk, and bile juice (9,38,47,49). Transplacental transmission from mother to child has been controversial, but postnatal transmission has been confirmed repeatedly (15,20,24,30,33,37,48,51,52,57 (39,44). Peripheral blood mononuclear cells act as a reservoir for TTV (41), but the highest viral load is found in the granulocytes (54). Viral transcription naturally occurs in bone marrow cells and not in peripheral blood mononuclear cells (40), although transcription in vitro has been achieved by DNA transfection into stimulated peripheral blood monocytes (29) and in a monkey cell line (19).A large number of full-length or near full-length genomes of TTV has been isolated from humans and primates. They have also been identified in farm animals (23), although the genomes of recent isolates from pigs, dogs, and cats proved to be considerably smaller in size than the TTV found in humans and primates (43). The highly conserved noncoding region constitutes about one-third of the genome. The coding region consists of a large open reading frame (ORF), ORF1, coding for the viral capsid protein as well as the smaller ORF2, ORF3, and ORF4. Additional mRNAs result from splicing events (19,40). Many different genotypes have been isolated, and an extremely wide range of DNA sequence divergence has been demonstrated (45). The steadily increasing number of new genotypes and the high sequence variability point to the need for a uniform and defined cla...

TTV infection in colorectal cancer tissues and normal mucosa

“…Sequence analyses of a number of isolates from the spleen of a Hodgkin's disease patient revealed single nucleotide changes leading to major modifications in the genome organization, even resulting in the expression of both modified and new viral proteins. 9 The identification of TT viruses as quasi-species was also confirmed in the same study, pointing to a continuous modification of a TT virus type within the same host. Nucleotide modifications within the highly conserved control region of the genome amplified however rarely occurred in these TT virus genomes 9 Chronic inflammation, often caused by infectious agents, inevitably causes tissue damage, thereby modifying the levels of expressed cellular proteins.…”

“…9 The identification of TT viruses as quasi-species was also confirmed in the same study, pointing to a continuous modification of a TT virus type within the same host. Nucleotide modifications within the highly conserved control region of the genome amplified however rarely occurred in these TT virus genomes 9 Chronic inflammation, often caused by infectious agents, inevitably causes tissue damage, thereby modifying the levels of expressed cellular proteins. 14 Chronic inflammatory disease such as ulcerative colitis, predispose patients to cancer development.…”

“…TT viruses phylogenetically group into 6 larger clusters, each consisting of smaller clusters of closer related TTV types. 9 Of note is the large number of sequences isolated from malignant and normal tissue from cancer patients, related to the TTV types saj-30 (n 5 70), ja10 (n 5 23), tchn-c1 (n 5 28) and saa-10 (n 5 24) (Figs. 1a and 1b).…”

“…[4][5][6][7] A broad spectrum of TT virus types has been detected and isolated from cancer tissue, including an elevated level in colon cancer, 8,9 but several attempts to link these viruses to the etiology of a specific disease have failed. 10,11 We determined the presence of TT virus DNA in tumor biopsies and normal colon tissue from patients (n 5 82) with colorectal cancer in comparison to colon samples taken from individuals (n 5 40) with normal endoscopic and histopathological findings.…”

Antigenic diversity and seroprevalences of Torque teno viruses in children and adults by ORF2-based immunoassays

“…Seroconversions occurred, except for TTV3 HEL32, at overall rates of 5-7 % of the initial seronegative sera, whilst a number of children that were initially seropositive for a single strain later acquired multiple-genogroup antibodies. This indicates that the simultaneous presence of several TTV genogroups in the human body (de Villiers et al, 2002;Jelcic et al, 2004;Maggi et al, 2005;Niel et al, 2000;Okamoto et al, 2001) can be due to sequential infections, and that antibodies against certain TTV types are non-protective against others. Interestingly, seroreversions were seen among all TTV strains, at rates of 10-75 % of the initial seropositive children, explaining the lower seroprevalences among children aged 4-7 years.…”