Heterogeneous distribution of TT virus of distinct genotypes in multiple tissues from infected humans

Association Between Torque Teno Virus and Systemic Immunodeficiency in Patients With Uveitis With a Suspected Infectious Etiology

PURPOSE

To determine the correlation between the presence of torque teno virus (TTV) in the aqueous humor of patients with uveitis and clinical information, including immunodeficiency history.

DESIGN

Multicenter, retrospective, cross-sectional study.

METHODS

Fifty-eight patients with uveitis with a suspected infectious etiology and 24 controls with cataract or age-related macular degeneration were included. We used quantitative polymerase chain reaction to test all subjects for TTV and multiplex polymerase chain reaction to test uveitis subjects for common ocular pathogens. When possible, both serum and aqueous humor samples were tested. Ocular TTV positivity was compared with age, sex, and a history of systemic immunodeficiency with logistic analysis.

RESULTS

Ocular TTV positivity was found in 23%, 11%, and 0% of patients with herpetic uveitis, nonherpetic uveitis, and controls, respectively. Among patients with herpes infection, positivity for ocular TTV was found in 43%, 8%, 14%, and 50% of patients with cytomegalovirus retinitis, iridocyclitis, acute retinal necrosis, and Epstein-Barr virus-positive uveitis, respectively. Patients with cytomegalovirus retinitis showed a significantly higher rate of ocular TTV infection than controls (P = .008). Serum analysis revealed TTV positivity in 90% of patients with uveitis and in 100% of controls. Age- and gender-adjusted logistic analysis revealed a correlation between ocular TTV positivity and systemic immunodeficiency (P = .01), but no correlations between ocular TTV and age, gender, or viral pathogenic type.

CONCLUSIONS

These findings suggest that positivity for ocular TTV was correlated with a clinical history of systemic immunodeficiency.

Detection and genetic characterization of the novel torque teno virus group 6 in Taiwanese general population

Torque teno virus (TTV) is one of the most common human viruses and can infect an individual with multiple genotypes chronically and persistently. TTV group 6 is a recently discovered phylogenetic group first isolated from eastern Taiwan indigenes, but whether the TTV group 6 was also prevalent in the general population still unknown. One hundred and three randomly collected blood samples from general population and 66 TTV positive DNA samples extracted from Taiwan indigenes were included. A group-6-specific PCR was developed for re-screen over TTV positive samples. Two TTV group 6 positive samples from general population were cloned and sequenced for identifying mix-infected TTVs and confirming their classification by maximum-likelihood and Bayesian inference phylogeny. TTV group 6 can be detected in 4.5% (4/89) and 7.6% (5/66) of TTV positive samples from Taiwanese general population and eastern Taiwan indigenes, respectively. Sample VC09 was mix-infected with TTV groups 3 and 6. Sample VC99 was mix-infected with TTV groups 3, 4 and 6. A highly diverse triple overlapping region was observed, which may represent a unique phenomenon of TTV. The group-6-specific PCR can successfully detect TTV group 6. TTV group 6 may be prevalent worldwide regardless of the geographic region and/or ethnic groups.

Taxonomic update for mammalian anelloviruses (family Anelloviridae)

Anelloviruses are small negative-sense single-stranded DNA viruses with genomes ranging in size from 1.6 to 3.9 kb. The family Anelloviridae comprised 14 genera before the present changes. However, in the last five years, a large number of diverse anelloviruses have been identified in various organisms. Here, we undertake a global analysis of mammalian anelloviruses whose full genome sequences have been determined and have an intact open reading frame 1 (ORF1). We established new criteria for the classification of anelloviruses, and, based on our analyses, we establish new genera and species to accommodate the unclassified anelloviruses. We also note that based on the updated species demarcation criteria, some previously assigned species (n = 10) merge with other species. Given the rate at which virus sequence data are accumulating, and with the identification of diverse anelloviruses, we acknowledge that the taxonomy will have to be dynamic and continuously evolve to accommodate new members.

A novel anellovirus from hospitalized neonates

Here, using viral metagenomics combined with conventional PCR, the complete genome sequence of a novel anellovirus (named anel-ch-zj and GenBank no. MT157223) from nasopharynx secretion specimens from hospitalized neonates was determined, and the deduced amino acid sequence of its ODF1 protein was found to be only 33.19%-39.33% identical to those of related anelloviruses with sequences available in the GenBank database, suggesting that it represents a putative new genus within the family Anelloviridae. PCR screening of 135 samples (including 45 nasopharynx secretion, 45 blood, and 45 fecal specimens collected from 45 individual hospitalized neonates) indicated that two nasopharynx secretion, two blood, and four fecal samples were positive for anel-ch-zj. Further PCR screening of 50 blood samples, 115 fecal samples, and 396 nasopharynx secretions collected from hospitalized children 1-5 years old did not yield any positive results. Whether this novel anellovirus detected in neonates is associated with specific diseases needs future investigation.

Associations Between Sputum Torque Teno Virus Load and Lung Function and Disease Severity in Patients With Chronic Obstructive Pulmonary Disease

Purpose: Viral load of Torque Teno virus (TTV) is elevated in immunosuppressed patients. The weakened immune response is typical in chronic obstructive pulmonary disease (COPD) patients. However, the relationship between TTV and COPD is still unknown.

Patients and Methods: We enrolled 91 patients admitted to hospitals with acute exacerbation of COPD (AECOPD) between January 2017 and August 2017 (ClinicalTrials.gov ID, NCT03236480). Sputum samples were gathered during hospitalization and the 120-day follow-up. TTV distribution and genogroups were assessed, and the associations between viral loads and clinical parameters were analyzed.

Results: TTV DNA was detected in 95.6% of COPD patients, and the viral load was nearly invariable at the stable and exacerbation states. Most TTV DNA-positive patients carried four distinct genotypes. Sputum load of TTV was positively associated with RV/TLC (r = 0.378, p = 0.030), and negatively correlated with FEV1/pre and FEV1/FVC (r = −0.484, −0.432, p = 0.011, 0.024, respectively). Neutral correlation between the TTV DNA load and COPD assessment test (CAT) scores (r = 0.258, p = 0.018) was observed.

Conclusion: Sputum loads of TTV DNA could be a novel indicator for lung function and disease severity assessment in COPD patients.

Torque teno viral load reflects immunosuppression in paediatric kidney-transplanted patients-a pilot study

BACKGROUND

Chronic deterioration of kidney graft function is related to inadequate immunosuppression (IS). A novel tool to assess the individual net state of IS in transplanted patients might be the monitoring of Torque teno virus (TTV) viral load. TTV is a non-pathogen virus detectable in almost all individuals. TTV level in the peripheral blood has been linked to the immune-competence of its host and should thus reflect IS after solid organ transplantation.

METHODS

TTV plasma load was quantified monthly by RT-PCR for a period of 1 year in 45 kidney-transplanted children. Post-transplant time was at least 3 months. The relation of the virus DNA levels to IS and transplant-specific clinical and laboratory parameters was analysed longitudinally.

RESULTS

TTV DNA was detectable in 94.5% of the plasma samples. There was a significant association with the post-transplant follow-up time as well as with the type of IS regimen, with lower virus loads in patients after longer post-transplant time and mTOR inhibitor-based IS. Furthermore, a significant positive correlation with the dose of prednisolone and mycophenolate mofetil was found.

CONCLUSIONS

TTV levels show an association/correlation with the strength of IS. Further studies are needed in order to evaluate TTV measurement as a tool for IS monitoring for hard clinical outcomes such as presence of donor-specific antibodies, rejections or infections-common consequences of insufficient or too intense IS.

Constant companion: clinical and developmental aspects of torque teno virus infections

Torque teno virus (TTV) is a commensal human virus observed as a circular single-negative-strand DNA molecule in various tissues and biological samples, notably in blood serum and lymphocytes. TTV has no apparent clinical significance, although it might be very useful as a prospective tool for gene delivery or as an epidemiological marker. Human populations are ubiquitously infected with TTV; the prevalence may reach 100%. The majority of babies become spontaneously infected with TTV, so that by the end of the first year of life, the prevalence reaches 'adult' values. TTV positivity in healthy early infancy and the presence of TTV in umbilical cord blood samples have been reported. The mechanism of infection and the dynamics of TTV prevalence in infants with age remain understudied. Meanwhile, the potential diagnostic and prognostic value of TTV as a marker deserves special attention and study, along with the possibility, causes and consequences of placental transmission of TTV under normal or pathological conditions.

Beyond Cytomegalovirus and Epstein-Barr Virus: a Review of Viruses Composing the Blood Virome of Solid Organ Transplant and Hematopoietic Stem Cell Transplant Recipients

Viral primary infections and reactivations are common complications in patients after solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) and are associated with high morbidity and mortality. Among these patients, viral infections are frequently associated with viremia. Beyond the usual well-known viruses that are part of the routine clinical management of transplant recipients, numerous other viral signatures or genomes can be identified in the blood of these patients. The identification of novel viral species and variants by metagenomic next-generation sequencing has opened up a new field of investigation and new paradigms. Thus, there is a need to thoroughly describe the state of knowledge in this field with a review of all viral infections that should be scrutinized in high-risk populations. Here, we review the eukaryotic DNA and RNA viruses identified in blood, plasma, or serum samples of pediatric and adult SOT/HSCT recipients and the prevalence of their detection, with a particular focus on recently identified viruses and those for which their potential association with disease remains to be investigated, such as members of the Polyomaviridae, Anelloviridae, Flaviviridae, and Astroviridae families. Current knowledge of the clinical significance of these viral infections with associated viremia among transplant recipients is also discussed. To ensure a comprehensive description in these two populations, individuals described as healthy (mostly blood donors) are considered for comparative purposes. The list of viruses that should be on the clinicians' radar is certainly incomplete and will expand, but the challenge is to identify those of possible clinical significance.

Dual infection and recombination of Kaposi sarcoma herpesvirus revealed by whole-genome sequence analysis of effusion samples

Kaposi sarcoma herpesvirus (KSHV) is the etiological agent of three malignancies, Kaposi sarcoma (KS), primary effusion lymphoma (PEL) and KSHV-associated multicentric Castelman disease. KSHV infected patients may also have an interleukin six-related KSHV-associated inflammatory cytokine syndrome. KSHV-associated diseases occur in only a minority of chronically KSHV-infected individuals and often in the setting of immunosuppression. Mechanisms by which KSHV genomic variations and systemic co-infections may affect the pathogenic pathways potentially leading to these diseases have not been well characterized in vivo. To date, the majority of comparative genetic analyses of KSHV have been focused on a few regions scattered across the viral genome. We used next-generation sequencing techniques to investigate the taxonomic groupings of viruses from malignant effusion samples from fourteen participants with advanced KSHV-related malignancies, including twelve with PEL and two with KS and elevated KSHV viral load in effusions. The genomic diversity and evolutionary characteristics of nine isolated, near full-length KSHV genomes revealed extensive evidence of mosaic patterns across all these genomes. Further, our comprehensive NGS analysis allowed the identification of two distinct KSHV genome sequences in one individual, consistent with a dual infection. Overall, our results provide significant evidence for the contribution of KSHV phylogenomics to the origin of KSHV subtypes. This report points to a wider scope of studies to establish genome-wide patterns of sequence diversity and define the possible pathogenic role of sequence variations in KSHV-infected individuals.

Molecular Epidemiology of Anellovirus Infection in Children's Urine: A Cross-sectional Study

Background

Anelloviridae is a viral family which is considered as a constant component of human virome. Given the ubiquitous nature of the virus infection and the long-standing relationship between the virus and the host, in the present study, we aimed at investigating the presence of Anelloviruses in the urine samples of children in a cross-sectional study.

Materials and Methods

The urine samples of 50 children who were referred to Hazrat Ali Asghar Children's Hospital, affiliated to Iran University of Medical Sciences, Tehran, Iran, were obtained. Three TaqMan real-time polymerase chain reactions (PCRs) were carried out for Anellovirus detection. A phylogenetic tree was drawn for positive products after PCR amplification, purification, and nucleotide sequencing. SPSS, version 20, was used for statistical analyses.

Results

Children's mean age ± standard deviation was 4.30 ± 1.47 years and 56% (28/50) were female. Real-time PCR revealed that Anellovirus was positive in 12% (6/50). Furthermore, PCR-sequencing results showed that torque teno virus was detected in 83.3% (5/6) and SEN virus in 16.6% (1/6) of the Anellovirus positive samples. In addition, 86% (5/6) of the children with positive samples were female. No significant difference was detected between any of the demographic characteristics and Anellovirus positivity (P > 0.05).

Conclusion

According to our preliminary study, the presence of Anelloviruses in the urine samples of asymptomatic children in Iran is striking, although limited sample size and age range limitations might have affected the comprehensive results of our study.

Molecular prevalence and genotypes of human pegivirus-1 (HPgV-1) and SENV-like viruses among multiply transfused patients with beta-thalassemia

Due to the high number of transfusions which patients with hereditary hemoglobinopathies (thalassemia, sickle cell disease) receive, they represent high risk of acquiring parenterally transmitted infectious diseases. In this respect, non pathogenic human commensal viruses, which also demonstrate parenteral transmission routes might also be acquired. One of the most widely spread parenterally-transmitted human commensal viruses include the Human Pegivirus-1 (HPgV-1, GBV-C) and Torque teno viruses (TTV) including its SEN virus-like (SENV) forms. The objective of this study was to evaluate the prevalence of HPgV-1 RNA and SENV-like viruses, among a group of patients with beta-thalassemia from a Blood Transfusion Center in the São Paulo State, Brazil. The prevalence of HPgV-1 RNA was 14.3 % (n = 6/42) and all of the positive samples were characterized as belonging to genotype 2 (83.3 % were referred to subgenotype 2A and 16.7 % to 2B). The prevalence of SENV-like viruses was 28.6 % (n = 12/42). SENV-like viruses of the genotypes SENV-H and SENV-A were classified during the performed phylogenetic analysis. Our study came as a continuation of a viral metagenomic survey among multiple transfused patients with beta-thalassemia. The obtained results shed a light on the prevalence and genotype distribution of commensal parenterally transmitted viruses like HPgV-1 and SENV in this specific population. However, more studies are needed to evaluate the clinical impact of these apparently non-pathogenic viruses in patients with thalassemia and their significance for the hemotherapy.

Bidirectional transfer of Anelloviridae lineages between graft and host during lung transplantation

Solid organ transplantation disrupts virus-host relationships, potentially resulting in viral transfer from donor to recipient, reactivation of latent viruses, and new viral infections. Viral transfer, colonization, and reactivation are typically monitored using assays for specific viruses, leaving the behavior of full viral populations (the "virome") understudied. Here we sought to investigate the temporal behavior of viruses from donor lungs and transplant recipients comprehensively. We interrogated the bronchoalveolar lavage and blood viromes during the peritransplant period and 6-16 months posttransplant in 13 donor-recipient pairs using shotgun metagenomic sequencing. Anelloviridae, ubiquitous human commensal viruses, were the most abundant human viruses identified. Herpesviruses, parvoviruses, polyomaviruses, and bacteriophages were also detected. Anelloviridae populations were complex, with some donor organs and hosts harboring multiple contemporaneous lineages. We identified transfer of Anelloviridae lineages from donor organ to recipient serum in 4 of 7 cases that could be queried, and immigration of lineages from recipient serum into the allograft in 6 of 10 such cases. Thus, metagenomic analyses revealed that viral populations move between graft and host in both directions, showing that organ transplantation involves implantation of both the allograft and commensal viral communities.

Viral metagenomics revealed novel betatorquevirus species in pediatric inpatients with encephalitis/meningoencephalitis from Ghana

The cause of acute encephalitis/meningoencephalitis in pediatric patients remains often unexplained despite extensive investigations for large panel of pathogens. To explore a possible viral implication, we investigated the virome of cerebrospinal fluid specimens of 70 febrile pediatric inpatients with clinical compatible encephalitis/meningoencephalitis. Using viral metagenomics, we detected and genetically characterized three novel human Torque teno mini virus (TTMV) species (TTMV-G1-3). Phylogenetically, TTMV-G1-3 clustered in three novel monophyletic lineages within genus Betatorquevirus of the Anelloviridae family. TTMV-G1-3 were highly prevalent in diseased children, but absent in the healthy cohort which may indicate an association of TTMV species with febrile illness. With 2/3 detected malaria co-infection, it remains unclear if these novel anellovirus species are causative agents or increase disease severity by interaction with malaria parasites. The presence of the viruses 28 days after initiating antimalarial and/or antibiotic treatment suggests a still active viral infection likely as effect of parasitic and/or bacterial co-infection that may have initiated a modulated immune system environment for viral replication or a defective virus clearance. This study increases the current knowledge on the genetic diversity of TTMV and strengthens that human anelloviruses can be considered as biomarkers for strong perturbations of the immune system in certain pathological conditions.

Prevalence and Genotyping of Torque Teno Virus in HBV/HIV and Chronic HBV Patients in Iran

Background:

Torque teno virus (TTV) was the first human Anelloviridae detected in a Japanese patient with an unknown type of hepatitis in 1997. TTV is by far the first known single-stranded circular DNA virus infecting human. In spite of its widespread nature in human population, its pathogenesis is still unclear. In addition, information regarding TTV infection in Iranian population is limited. Therefore, we attempted to determine the prevalence and genotype of

TTV in three groups:

HIV/HBV patients, chronic hepatitis B patients, and healthy individuals.

Methods:

The presence of TTV DNA in sera was investigated using PCR. The primer sets encompassing two 5’-UTR and N22 regions were used, and the positive products were collected for sequencing. Phylogenetic tree was generated based on N22 region and using the MEGA 7 software.

Results:

TTV DNA was detected in 452 patients with HIV/HBV and chronic hepatitis B, as well as in healthy control groups. The results from PCR indicated positive rates for these three groups 48%, 54%, and 49.3% using 5’-UTR primer and 15.1%, 12%, and 8% using N22 primer, respectively.

Conclusion:

Five genogroups were observed, which the second group was found to be the most frequent. The results of 5’-UTR primer showed more prevalence of TTV DNA comparing to N22 primer in patients and healthy control.

Two new species of betatorqueviruses identified in a human melanoma that metastasized to the brain

The role of viral infections in the etiology of brain cancer remains uncertain. Prior studies mostly focused on transcriptome or viral DNA integrated in tumor cells. To investigate for the presence of viral particles, we performed metagenomics sequencing on viral capsid-protected nucleic acids from 12 primary and 8 metastatic human brain tumors. One brain tumor metastasized from a skin melanoma harbored two new human anellovirus species, Torque teno mini virus Emory1 (TTMV Emory1) and Emory2 (TTMV Emory2), while the remaining 19 samples did not reveal any exogenous viral sequences. Their genomes share 63-67% identity with other TTMVs, and phylogenetic clustering supports their classification within the Betatorquevirus genus. This is the first identification of betatorqueviruses in brain tumors. The viral DNA was in its expected non-integrated circular form, and it is unclear if the viruses contributed to tumor formation. Whether the viruses originated from blood, or the primary skin tumor could not be ascertained. Overall, our results demonstrate the usefulness of viral metagenomics to detect previously unknown exogenous virus in human brain tumors. They further suggest that active viral infections are rare events in brain tumors, but support a follow-up larger scale study to quantify their frequency in different brain tumor subtypes.

The Perioperative Lung Transplant Virome: Torque Teno Viruses Are Elevated in Donor Lungs and Show Divergent Dynamics in Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a principal cause of early morbidity and mortality after lung transplantation, but its pathogenic mechanisms are not fully clarified. To date, studies using standard clinical assays have not linked microbial factors to PGD. We previously used comprehensive metagenomic methods to characterize viruses in lung allografts >1 mo after transplant and found that levels of Anellovirus, mainly torque teno viruses (TTVs), were significantly higher than in nontransplanted healthy controls. We used quantitative polymerase chain reaction to analyze TTV and shotgun metagenomics to characterize full viral communities in acellular bronchoalveolar lavage from donor organs and postreperfusion allografts in PGD and non-PGD lung transplant recipient pairs. Unexpectedly, TTV DNA levels were elevated 100-fold in donor lungs compared with healthy adults (p = 0.0026). Although absolute TTV levels did not differ by PGD status, PGD cases showed a smaller increase in TTV levels from before to after transplant than did control recipients (p = 0.041). Metagenomic sequencing revealed mainly TTV and bacteriophages of respiratory tract bacteria, but no viral taxa distinguished PGD cases from controls. These findings suggest that conditions associated with brain death promote TTV replication and that greater immune activation or tissue injury associated with PGD may restrict TTV abundance in the lung.

Does Teno Torque Virus Induce Autoimmunity After Hematopoietic Stem Cell Transplantation? A Case Report

Teno Torque virus, member of the family of Anelloviridae, has been associated with many autoimmune diseases such as idiopathic hepatitis, systemic lupus erythematosus, and multiple sclerosis. Its viral load tends to be higher in the bone marrow and in tissues with high turnover rate. We report here a case of an 11-month-old infant affected by acute myeloid leukemia who underwent hematopoietic stem cell transplantation, and after 6 months had autoimmune hepatitis and atopic dermatitis. Extremely high-cytokine IP-10 and eotaxin levels were found in her sera, and serological tests and RT-PCR for viruses showed positive results exclusively for Teno Torque virus.

Human anelloviruses: an update of molecular, epidemiological and clinical aspects

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.

Molecular characterization of Torque teno virus and SEN virus co-infection with HIV in patients from Southern Iran

INTRODUCTION

Torque teno virus (TTV) and SEN virus are circular single-stranded DNA viruses that cause blood-borne infections. The SEN virus (SEN-V) was originally detected in the serum of an injection drug user infected with human immunodeficiency virus (HIV). Recently TTV was discovered as a potential causative agent of non-A-E hepatitis. The aim of this study was to investigate the prevalence of the SEN-V-D/H and TTV in HIV patients and healthy blood donors in Iran.

METHODS

One hundred and fifty HIV patients with a mean age of 50.46 ± 18.46 years and 150 healthy blood donors with a mean age of 48.16 ± 13.73 years were included in this study. TTV and SEN-V were detected by the PCR and were quantitatively assayed by competitive PCR (nested and semi-nested PCR). Restriction fragment length polymorphisms (RFLPs) were used to determine the heterogeneity of TTV.

RESULTS

TTV and SEN-V were detected 96 (64%) and 84 (56%) of 150 HIV patients respectively. These rates were 34% (n=51) and 37.33% (n=56) in healthy blood donors (significant, p<0.05). PCR detected SEN-V/TTV DNA from 32 of the healthy blood donors (21.33%), while 65 (43.33%) of HIV patients were positive for SEN-V/TTV DNA. Of 150 HIV patients, 32.66% and 23.33% were positive for SEN-V-H and SEN-V-D, respectively and 18.66% (n=28) were co-infected with SEN-V-D/H.

CONCLUSIONS

The prevalence of SEN-VD/H and TTV is higher in HIV patients than in healthy blood donors in Southern Iran. Our results suggest that TTV and SEN-V might play a role in the development of liver disease in patients with immunodeficiency diseases.

Identification of novel anelloviruses with broad diversity in UK rodents

Anelloviruses are a family of small circular ssDNA 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, 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 organization consistent with other anelloviruses, but form two clear phylogenetic groups that are as distinct from each other as from defined genera.

High-throughput sequencing exclusively identified a novel Torque teno virus genotype in serum of a patient with fatal fever

Torque teno virus (TTV) has been found to be prevalent world-wide in healthy populations and in patients with various diseases, but its etiological role has not yet been determined. Using high-throughput unbiased sequencing to screen for viruses in the serum of a patient with persistent high fever who died of suspected viral infection and prolonged weakness, we identified the complete genome sequence of a TTV (isolate Hebei-1). The genome of TTV-Hebei-1 is 3649 bp in length, encoding four putative open reading frames, and it has a G+C content of 49%. Genomic comparison and a BLASTN search revealed that the assembled genome of TTV-Hebei-1 represented a novel isolate, with a genome sequence that was highly heterologous to the sequences of other reported TTV strains. A phylogenetic tree constructed using the complete genome sequence showed that TTV-Hebei-1 and an uncharacterized Taiwanese strain, TW53A37, constitute a new TTV genotype. The patient was strongly suspected of carrying a viral infection and died eventually without any other possible causes being apparent. No virus other than the novel TTV was identified in his serum sample. Although a direct causal link between the novel TTV genotype infection and the patient's disease could not be confirmed, the findings suggest that surveillance of this novel TTV genotype is necessary and that its role in disease deserves to be explored.

Identification of a new genotype of Torque Teno Mini virus

Background

Although human torque teno viruses (TTVs) were first discovered in 1997, still many associated aspects are not clarified yet. The viruses reveal a remarkable heterogeneity and it is possible that some genotypes are more pathogenic than others. The identification of all genotypes is essential to confirm previous pathogenicity data, and an unbiased search for novel viruses is needed to identify TTVs that might be related to disease.

Method

The virus discovery technique VIDISCA-454 was used to screen serum of 55 HIV-1 positive injecting drug users, from the Amsterdam Cohort Studies, in search for novel blood-blood transmittable viruses which are undetectable via normal diagnostics or panvirus-primer PCRs.

Results

A novel torque teno mini virus (TTMV) was identified in two patients and the sequence of the full genomes were determined. The virus is significantly different from the known TTMVs (< 40% amino acid identity in ORF1), yet it contains conserved characteristics that are also present in other TTMVs. The virus is chronically present in both patients, and these patients both suffered from a pneumococcal pneumonia during follow up and had extremely low B-cells counts.

Conclusion

We describe a novel TTMV which we tentatively named TTMV-13. Further research is needed to address the epidemiology and pathogenicity of this novel virus.

Describing the silent human virome with an emphasis on giant viruses

Viruses are the most abundant obligate intracellular entities in our body. Until recently, they were only considered to be pathogens that caused a broad array of pathologies, ranging from mild disease to deaths in the most severe cases. However, recent advances in unbiased mass sequencing techniques as well as increasing epidemiological evidence have indicated that the human body is home to diverse viral species under non-pathological conditions. Despite these studies, the description of the presumably healthy viral flora, i.e. the normal human virome, is still in its infancy regarding viral composition and dynamics. This review summarizes our current knowledge of the human virome under non-pathological conditions.

Identification of episomal human papillomavirus and other DNA viruses in cytological anal samples of HIV-uninfected men who have sex with men

To date, there have been only few studies that investigated integration of anal Human Papillomavirus (HPV). Most of them were conducted on HIV-infected individuals and mainly analyzed samples from high-grade lesions and invasive cancer. We aimed to investigate HPV physical status in HIV-negative men who have sex with men (MSM) with a detectable anal HPV infection, irrespective of the presence of lesions. We also sought to explore the presence of other circular DNA viruses in the anal region. Study participants were attendees of an STI screening program, which were also screened for anal HPV infection and cytological abnormalities. HPV physical status was assessed using multiply-primed RCA. HPV16-positive samples were also analyzed using E2/E6 multiplex PCR, qRT-PCR and APOT assay. RCA and virus-specific PCR were employed to investigate the presence of other DNA viruses. Anal HPV infection was detected in 76.9% of the 230 MSM enrolled. The anal cytological reports were: 129 NILM, 37 ASC-US and 28 L-SIL (36 samples were inadequate for interpretation). HPV physical status was evaluated in the 109 anal specimens that harbored one or two different HPV genotypes. Integration was observed only in one HPV16-positive sample (0.9%), in which integrate-derived viral transcripts of type B were detected. Integration occurred in chromosome 14 q. In 22 of the 53 (41.5%) mucosal HPV-negative samples, RCA restriction results would seem to indicate the presence of circular DNA viruses. Indeed, cutaneous HPV (4 samples), MCPyV (5 samples) and TTV (4 samples) were detected. In conclusion, anal HPV integration was rarely evidenced in HIV-uninfected MSM with no or mild anal cytological abnormalities, although the integration rate may have been underestimated because of the limitations of the employed assays. Other DNA viruses were detected in the anal samples of these individuals, although the significance of this occurrence needs to be assessed.

Validation of SYBR Green based quantification assay for the detection of human Torque Teno virus titers from plasma

Background

Quantification of titers of ubiquitous viruses such as Torque teno virus (TTV) that do not cause clinical symptoms might be helpful in assessing the immune status of an individual. We hereby describe the validation of a SYBR Green-based TTV quantification method for plasma samples.

Methods

Plasmids with TTV specific inserts were used for preparing standards and absolute quantification of TTV was performed using SYBR Green methodology. The method was assessed for its accuracy and precision (intra and inter-day) on four non-consecutive days. TTV was also quantified from plasma samples of 20 healthy volunteers and from 30 hematopoietic stem cell transplant (HSCT) recipients.

Results

The assay was specific and showed satisfactory efficiency (82.2%, R²=0.99) with the limit of quantification defined as 100 copies per reaction. The assay had good precision (inter and intra-day coefficient of variation in cycle threshold (C_T) < 4%) and accuracy (100 ± 10%) in the range of 100 to 10¹⁰ copies/reaction. We found TTV loads ranging from 2.5 – 4.07 log copies/mL of plasma with C_T (mean ± SD) of 33.8 ± 1.77 in healthy individuals and 2.06 – 8.49 log copies/mL of plasma with C_T (mean ± SD) of 24.3 ± 1.04 in HSCT recipients.

Conclusion

SYBR Green-based q-PCR assay combines simplicity with satisfactory sensitivity and may be suitable for monitoring the immune status of transplant recipients, where TTV loads over time may serve as a marker for immune reconstitution in human plasma samples.

Increased prevalence of anellovirus in pediatric patients with fever

The Anelloviridae family consists of non-enveloped, circular, single-stranded DNA viruses. Three genera of anellovirus are known to infect humans, named TTV, TTMDV, and TTMV. Although anelloviruses were initially thought to cause non-A-G viral hepatitis, continued research has shown no definitive associations between anellovirus and human disease to date. Using high-throughput sequencing, we investigated the association between anelloviruses and fever in pediatric patients 2–36 months of age. We determined that although anelloviruses were present in a large number of specimens from both febrile and afebrile patients, they were more prevalent in the plasma and nasopharyngeal (NP) specimens of febrile patients compared to afebrile controls. Using PCR to detect each of the three species of anellovirus that infect humans, we found that anellovirus species TTV and TTMDV were more prevalent in the plasma and NP specimens of febrile patients compared to afebrile controls. This was not the case for species TTMV which was found in similar percentages of febrile and afebrile patient specimens. Analysis of patient age showed that the percentage of plasma and NP specimens containing anellovirus increased with age until patients were 19–24 months of age, after which the percentage of anellovirus positive patient specimens dropped. This trend was striking for TTV and TTMDV and very modest for TTMV in both plasma and NP specimens. Finally, as the temperature of febrile patients increased, so too did the frequency of TTV and TTMDV detection. Again, TTMV was equally present in both febrile and afebrile patient specimens. Taken together these data indicate that the human anellovirus species TTV and TTMDV are associated with fever in children, while the highly related human anellovirus TTMV has no association with fever.

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

Torque teno viruses (TTVs) circulate widely among humans, causing persistent viraemia in healthy individuals. Numerous TTV isolates with high genetic variability have been identified and segregated into 29 species of five major phylogenetic groups. To date, the diversity of TTV sequences, challenges in protein expression and the subsequent lack of serological assays have hampered TTV seroprevalence studies. Moreover, the antigenic relationships of different TTVs and their specific seroprevalences in humans remain unknown. For five TTV strains--belonging to different species of four genogroups--we developed, using recombinant glutathione S-transferase (GST)-fused TTV ORF2 proteins, glutathione-GST capture enzyme immunoassays (EIAs) detecting antibodies towards conformational epitopes. We then analysed serum samples from 178 healthy adults and 108 children; IgG reactivities were observed either towards a single strain or towards multiple strains, which pointed to antigenic distinction of TTV species. The overall seroprevalence for the five TTVs peaked at 43 % (18 of 42) in children 2-4 years of age, subsequently declined, and again reached 42 % (74 of 178) among adults. TTV6 species-specific IgG predominated in children, whereas that for TTV13 predominated in adults. During a 3 year follow-up of the same children, both species-specific seroconversions and seroreversions occurred. This is the first EIA-based study of different TTVs, providing a new approach for seroepidemiology and diagnosis of TTV infections. Our data suggest that different TTVs in humans may differ in antiviral antibody profiles, infection patterns and epidemiology.

Torque teno virus in fecal samples of patients with gastroenteritis: prevalence, genogroups distribution, and viral load

Torque teno virus (TTV, genus Alphatorquevirus, family Anelloviridae) is a DNA virus, highly prevalent in populations from around the world. TTV isolates have been classified into five main phylogenetic groups (1-5) showing a large genetic distance between them. The presence of TTV has been detected in feces. However, whether all five TTV genogroups are excreted in feces and the frequency of these events are presently unknown. The presence of TTV DNA was assessed in feces from 135 Brazilian (0-90 years old) patients with gastroenteritis by using three PCR methods, including real-time PCR. One hundred twenty one (91.1%) samples were positive with at least one method. Using a genogroup-specific assay, it was shown that all genogroups were present. Thirty-seven (27.4%), 27 (20.0%), 57 (42.2%), 29 (21.5%), and 33 (24.4%) fecal samples contained TTV isolates belonging to genogroups 1-5, respectively. Coinfections with two, three, four, and five TTV genogroups were found in 23 (17.0%), 15 (11.1%), 7 (5.2%), and 7 (5.2%) fecal samples, respectively. Thus, 52 (38.5%) samples contained more than one TTV genogroup. Viral loads ranged from 2.6 to 6.5 log genome equivalents per gram of feces. However, only moderate variations of viral load were noted depending on genogroup and number of coinfecting TTV genogroups. These results show a high prevalence and a diversity of TTV isolates in feces.

Comparison of diversity of torque teno virus 1 in different mucosal tissues and disorders

Diversity of TTV1 was assessed in the head and neck region in patients with potentially malignant (oral lichen planus, oral leukoplakia) and malignant lesions (oral and laryngeal squamous cell cancers) and was compared to that found in the uterine cervix (cervical atypia and cervical cancer) by directly sequencing the NG061-063 segment of ORF1. These sequences were classified by the formerly used genogroup-genotype system as well as by the newly accepted species classification by aligning with the corresponding region of the type sequences of the 29 TTV species. All sequences obtained during the study clustered together with the TTV1 type sequence; to express diversity within TTV1, genotypes and subtypes of the former classification were used.The commonest subtypes were 2c followed by 2b, 1a and 1b. Subtypes 2b and 2c were evenly distributed among cervical samples; subtype 1a was more frequent in patients with cervical atypia or cancer. Subtypes 2c was more frequent than 2b in head and neck lesions. In conclusion, genotype and even subtype distribution may be important in association with diseases, therefore using this classification for characterization of intraspecies diversity of TTV1 is proposed.

Human anelloviruses and the central nervous system

Torque teno virus and related anelloviruses are a recent addition to the list of agents that cause chronic productive infections and high levels of plasma viraemia in humans. Many aspects of the natural history and pathogenesis of these under many respects surprising viruses are still poorly understood. In this review, we briefly outline the general properties of anelloviruses, examine what is currently known about the interactions they establish with the central nervous system (CNS), and discuss the possible pathological consequences.

Age-related tissue distribution of swine Torque teno sus virus 1 and 2

Torque teno viruses (TTVs) are small, non-enveloped viruses with a circular single-stranded DNA genome, belonging to the family Anelloviridae. In swine, two genetically distinct species have been identified, Torque teno sus virus 1 (TTSuV1) and 2 (TTSuV2). The aim of the present work was to study the tissue distribution of TTSuV1 and TTSuV2 in pigs of different ages, including foetuses at the second and last thirds of gestation, and animals at 5 days and 5, 15 and 24 weeks of age. Investigated tissues included brain, lung, mediastinal and mesenteric lymph nodes, heart, liver, spleen, kidney and bone marrow. Viral DNA from tissue extractions were tested by a comparative PCR for the presence of TTSuVs. Overall, TTSuV1 and TTSuV2 species were found in all tissues tested, with variations depending on age, and following similar infection dynamics in all tissues, increasing progressively in prevalence and virus load over time. The highest prevalence was found at 5 weeks of age and maintained afterwards, and the highest loads of virus in the different tissues were seen in the oldest animals (15 and 24 weeks of age). No animals were negative to TTV, including foetuses. In conclusion, the present study indicated that swine TTSuV1 and TTSuV2 can be found virtually in all body tissues of the pig. Both swine TTV species were present in high levels in almost all older animals, while viral negative tissues were only found in 5-week-old and 5-day-old pigs, and foetuses.

Torquetenovirus DNA drives proinflammatory cytokines production and secretion by immune cells via toll-like receptor 9

Active infection with torquetenovirus (TTV) has been associated with an increased severity of diseases in which inflammation plays a particularly important pathogenetic role. Here, we report that cloned DNA of a genogroup 4 TTV (ViPiSAL) is an activator of proinflammatory cytokine production by murine spleen cells and that the effect is mediated via toll-like receptor (TLR)9. The same DNA also increased the levels of proinflammatory cytokines induced by two well-characterized TLR9 stimulants. Finally, in silico analyses of the genomes of ViPiSAL and other TTVs revealed marked differences in the representation of CpG motifs known to be most effective at activating immune cells via TLR9. These findings demonstrate for the first time that at least one TTV isolate has the potential to stimulate and co-stimulate inflammatory responses.

Detection of Torque teno virus in Epstein-Barr virus positive and negative lymph nodes of patients with Hodgkin lymphoma

The age-specific incidence of Hodgkin lymphoma (HL) is bimodal with peaks occurring among young adults (15 - 34 years old) and people older than 45 years. Epstein-Barr virus (EBV) is associated with only one-third of HL cases. This study sought to determine if Torque teno virus (TTV) might be independently associated with HL. The presence of EBV was appraised by in situ hybridization and immunohistochemistry in lymph node biopsies from 46 patients (3 - 81 years old) with HL. TTV DNA was assessed by PCR amplification. EBV was detected in 22 (48%) patients. TTV DNA was detected in 24/46 (52%) patients, as well as in 12/20 (60%) control patients with lymphoid unspecific hyperplasia. TTV DNA was not significantly more frequent in EBV negative (54%) than in EBV positive (50%) nodes. However, it was observed that the group of young adults (15 - 34 years, n = 19) showed the lowest EBV frequency (21%) but the highest TTV occurrence (60%). This may suggest an involvement of TTV infection in the pathogenesis of HL in young adults. Further large population-based studies are required to confirm our findings.

Detection of TT virus by single-primer sequence-independent amplification in multiple samples collected from an outbreak of gastroenteritis

A panel of gastroenteritis outbreak samples was subjected to a virus purification and concentration algorithm followed by a sequence-independent amplification method devised to detect viral enteric pathogens. The application of these methods allowed the identification of torque teno virus (TTV) in one outbreak. The complete genome sequence of 3,260 nt was obtained through "genome walking", and four open reading frames were deduced from the genomic sequence. Phylogenetic analysis grouped this virus in TTV genetic group 3, clustering with genotype 27, with 85% similarity at the nt level with strain SAa-01.

Novel anellovirus discovered from a mortality event of captive California sea lions

A viral metagenomic study was performed to investigate potential viral pathogens associated with a mortality event of three captive California sea lions (Zalophus californianus). This study identified a novel California sea lion anellovirus (ZcAV), with 35 % amino acid identity in the ORF1 region to feline anelloviruses. The double-stranded replicative form of ZcAV was detected in lung tissue, suggesting that ZcAV replicates in sea lion lungs. Specific PCR revealed the presence of ZcAV in the lung tissue of all three sea lions involved in the mortality event, but not in three other sea lions from the same zoo. In addition, ZcAV was detected at low frequency (11 %) in the lungs of wild sea lions. The higher prevalence of ZcAV and presence of the double-stranded replicative form in the lungs of sea lions from the mortality event suggest that ZcAV was associated with the death of these animals.

Intragenomic rearrangement in TT viruses: a possible role in the pathogenesis of disease

A role for the ubiquitous Torque teno (TT) viruses in the pathogenesis of disease has not been resolved. In vivo and in vitro intragenomic rearrangement of TT virus genomes has been demonstrated. Replication in cell culture of a subviral molecule (411 bp) occurs through oligomerisation of RNA transcripts. Although the functions of the respective TT viral genes, as well as the newly formed genes in the rearranged subviral molecules, are largely unknown, certain similarities to genes of plant viruses of the family Geminiviridae will be described. A degree of similarity to certain cellular genes poses the question as to a role of molecular mimicry in the pathogenesis of autoimmune disease and diabetes.

History of discoveries and pathogenicity of TT viruses

Since 1997, groups of novel nonenveloped DNA viruses with a circular, single-stranded (negative sense) DNA genome of 3.6-3.9 kb, 3.2 kb, or 2.8-2.9 kb in size have been discovered and designated Torque teno virus (TTV), Torque teno midi virus (TTMDV), and Torque teno mini virus (TTMV), respectively, in the floating genus Anellovirus. These three anelloviruses frequently and ubiquitously infect humans, and the infections are characterized by lifelong viremia and great genetic variability. Although TTV infection has been epidemiologically suggested to be associated with many diseases including liver diseases, respiratory disorders, hematological disorders, and cancer, there is no direct causal evidence for links between TTV infection and specific clinical diseases. The pathogenetic role of TTMV and TTMDV infections remains unknown. The changing ratio of the three anelloviruses to each other over time, relative viral load, or combination of different genotype(s) of each anellovirus may be associated with the pathogenicity or the disease-inducing potential of these three human anelloviruses. To clarify their disease association, polymerase chain reaction (PCR) systems for accurately detecting, differentiating, and quantitating all of the genotypes and/or genogroups of TTV, TTMDV, and TTMV should be established and standardized, as should methods to detect past infections and immunological responses to anellovirus infections.

TT viruses in animals

Infection with TT virus (Torque teno virus, TTV), a small, nonenveloped virus with a circular, single-stranded DNA genome classified in the floating genus Anellovirus, is not restricted to humans. Using highly conserved primers derived from the untranslated region of the human TTV genome, a variety of TTV-like viruses have been found circulating in nonhuman primates such as chimpanzees, macaques, and tamarins. TTV variants in nonhuman primates are species-specific, although some genetic groups of human and chimpanzee TTVs cluster to make human/chimpanzee clades. TTVs from macaques and tamarins are increasingly divergent from TTV variants infecting humans and chimpanzees. TTV-like mini virus (TTMV) infections have also been detected in chimpanzees, with genotypes distinct but interspersed with human TTMV genotypes. Pets are also naturally infected with species-specific TTVs, and several isolates have been found in cats and dogs. In addition, other mammals such as tupaias and pigs have species-specific TTVs: swine TTVs are found among pigs worldwide. The genomic organization and proposed transcriptional profiles of TTVs infecting nonhuman primate and other mammalian species are similar to those of human TTVs, and co-evolution of TTVs with their hosts has been suggested. To date, TTVs infecting nonhuman primates and other mammalian species have been under-examined. It is likely that essentially all animals are naturally infected with species-specific TTVs.

Immunobiology of the Torque teno viruses and other anelloviruses

Many features of the Torque teno virus and the other anelloviruses (AVs) that have been identified after this virus was discovered in 1997 remain elusive. The immunobiology of the AVs is no exception. However, evidence is progressively accumulating that at least some AVs have an interesting interplay with cells and soluble factors known to contribute to the homeostasis of innate and adaptive immunity. Evidence is also accumulating that this interplay can have a significant impact on how effectively an infected host can deal with superimposed infectious and non-infectious noxae. This review article discusses the scanty information available on these aspects and highlights the ones that would be more urgent to precisely understand in order to get an adequate assessment of how important for human health these extremely ubiquitous and pervasive viruses really are.

First description of swine Torque teno virus (TTV) and detection of a new genogroup in Hungary: short communication

Torque teno virus (TTV) belongs to the floating genus of Anellovirus. It was discovered in a human patient, and later it was also found in animals including pigs. The aim of this study was to investigate the presence and estimate the prevalence of swine TTV in Hungarian pig herds for the first time, and to characterise the viruses found. Serum samples of 82 adult swine from 13 piggeries and 44 weaned pigs from one large herd were tested by PCR for the presence of TTV DNA. Viral DNA was found in 30% of the adult swine and 73% of the weaned pigs tested. Liver and intestine of weaned pigs were also tested and found to be infected at a lower rate. The TTV sequences found in sera and intestines were similar and could be clustered as swine genogroup 1. However, the sequences derived from one liver were remarkably different from all other known genogroups and seemed to represent a new genogroup.

Quantification and genotyping of torque teno virus at a wastewater treatment plant in Japan

Torque teno virus (TTV) DNA was quantitatively detected in influent and effluent samples collected from a wastewater treatment plant in Japan, with the highest concentration being 4.8 x 10(4) copies/liter. Genogroup-specific nested PCR demonstrated that TTV of genogroup 3 was the most abundant in wastewater among the five genogroups tested.