Prevalence of TTV DNA and GBV-C RNA in patients with systemic sclerosis, rheumatoid arthritis, and osteoarthritis does not differ from that in healthy blood donors

Blood DNA virome associates with autoimmune diseases and COVID-19

Aberrant immune responses to viral pathogens contribute to pathogenesis, but our understanding of pathological immune responses caused by viruses within the human virome, especially at a population scale, remains limited. We analyzed whole-genome sequencing datasets of 6,321 Japanese individuals, including patients with autoimmune diseases (psoriasis vulgaris, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), pulmonary alveolar proteinosis (PAP) or multiple sclerosis) and coronavirus disease 2019 (COVID-19), or healthy controls. We systematically quantified two constituents of the blood DNA virome, endogenous HHV-6 (eHHV-6) and anellovirus. Participants with eHHV-6B had higher risks of SLE and PAP; the former was validated in All of Us. eHHV-6B-positivity and high SLE disease activity index scores had strong correlations. Genome-wide association study and long-read sequencing mapped the integration of the HHV-6B genome to a locus on chromosome 22q. Epitope mapping and single-cell RNA sequencing revealed distinctive immune induction by eHHV-6B in patients with SLE. In addition, high anellovirus load correlated strongly with SLE, RA and COVID-19 status. Our analyses unveil relationships between the human virome and autoimmune and infectious diseases.

Understanding torquetenovirus (TTV) as an immune marker

Torquetenovirus (TTV), a small, single stranded anellovirus, is currently being explored as a marker of immunocompetence in patients with immunological impairment and inflammatory disorders. TTV has an extremely high prevalence and is regarded as a part of the human virome, the replication of which is controlled by a functioning immune system. The viral load of TTV in plasma of individuals is thought to reflect the degree of immunosuppression. Measuring and quantifying this viral load is especially promising in organ transplantation, as many studies have shown a strong correlation between high TTV loads and increased risk of infection on one side, and low TTV loads and an increased risk of rejection on the other side. As clinical studies are underway, investigating if TTV viral load measurement is superior for gauging antirejection therapy compared to medication-levels, some aspects nevertheless have to be considered. In contrast with medication levels, TTV loads have to be interpreted bearing in mind that viruses have properties including transmission, tropism, genotypes and mutations. This narrative review describes the potential pitfalls of TTV measurement in the follow-up of solid organ transplant recipients and addresses the questions which remain to be answered.

Torque Teno Virus Quantification for Monitoring of Immunomodulation with Biological Compounds in the Treatment of Rheumatoid Arthritis

OBJECTIVES

Rheumatoid arthritis (RA) patients who fail to respond to methotrexate (MTX) can receive biologic disease-modifying antirheumatic drugs (bDMARDs). The Torque Teno Virus (TTV) is a potential novel candidate for monitoring of immunosuppression. We explore TTV in these patients and association with clinical response to bDMARDs.

METHODS

The BioBio Study is a multicentre randomized open-label trial, including RA patients with insufficient response to MTX. Patients were randomized to either TNFi (infliximab, INF), anti-IL-6 (tocilizumab, TCZ), CTLA4-Ig (abatacept, ABA) or anti-CD20 (rituximab, RTX) in addition to MTX. PCR was used to quantify TTV in the peripheral blood.

RESULTS

TTV was measured in 95 patients (INF, n = 23; TCZ, n = 22; ABA, n = 27; RTX; n = 23). TTV increased by a median of 4.5*104 copies/ml (c/ml; inter quartile range [IQR] 0-7.5*105) after 3 months. TTV levels at month 3 were associated with SDAI (p= 0.03) and CDAI response (p= 0.026) at month 6. A TTV cut-off level of 1.2*106 c/ml at month 3 had a positive likelihood ratio of 2.7 for prediction of SDAI85% response at month 6.

CONCLUSION

Our data suggest that TTV levels increase upon TNF, CD20 and co-stimulation blockade and associate with clinical response to bDMARDs in RA patients.

TRIAL REGISTRATION

ClinicalTrials.gov; https://clinicaltrials.gov; NCT01638715.

Viruses with Circular Single-Stranded DNA Genomes Are Everywhere!

Circular single-stranded DNA viruses infect archaea, bacteria, and eukaryotic organisms. The relatively recent emergence of single-stranded DNA viruses, such as chicken anemia virus (CAV) and porcine circovirus 2 (PCV2), as serious pathogens of eukaryotes is due more to growing awareness than to the appearance of new pathogens or alteration of existing pathogens. In the case of the ubiquitous human circular single-stranded DNA virus family Anelloviridae, there is still no convincing direct causal relation to any specific disease. However, infections may play a role in autoimmunity by changing the homeostatic balance of proinflammatory cytokines and the human immune system, indirectly affecting the severity of diseases caused by other pathogens. Infections with CAV (family Anelloviridae, genus Gyrovirus) and PCV2 (family Circoviridae, genus Circovirus) are presented here because they are immunosuppressive and affect health in domesticated animals. CAV shares genomic organization, genomic orientation, and common features of major proteins with human anelloviruses, and PCV2 DNA may be present in human food and vaccines.

Metagenomics analysis of red blood cell and fresh-frozen plasma units

BACKGROUND

Although the risk of transmitting infectious agents by blood transfusion is dramatically reduced after donor selection, leukoreduction, and laboratory testing, some could still be present in donor's blood. A description of metagenomes in blood products eligible for transfusion represents relevant information to evaluate the risk of pathogen transmission by transfusion.

STUDY DESIGN AND METHODS

Detection of viruses, bacteria, and fungi genomes was made by high-throughput sequencing (HTS) of 600 manufactured blood products eligible for transfusion: 300 red blood cell (RBC) and 300 fresh-frozen plasma (FFP) units.

RESULTS

Anelloviruses and human pegivirus, frequent in the blood of healthy individuals, were found. Human papillomavirus type 27 and Merkel cell polyomavirus, present on the skin, were also detected. Unexpectedly, astrovirus MLB2 was identified and characterized in a FFP unit. The presence of astrovirus MLB2 was confirmed in donor's blood and corresponded to an asymptomatic acute viremia. Sequences of bacteria and fungi were also detected; they are likely the result of environmental contamination.

CONCLUSION

This study demonstrates that HTS is a promising tool for detecting common and less frequent infectious pathogens in blood products.

Human endogenous retrovirus W activity in cartilage of osteoarthritis patients

The etiology of viruses in osteoarthritis remains controversial because the prevalence of viral nucleic acid sequences in peripheral blood or synovial fluid from osteoarthritis patients and that in healthy control subjects are similar. Until now the presence of virus has not been analyzed in cartilage. We screened cartilage and chondrocytes from advanced and non-/early osteoarthritis patients for parvovirus B19, herpes simplex virus-1, Epstein Barr virus, cytomegalovirus, human herpes virus-6, hepatitis C virus, and human endogenous retroviruses transcripts. Endogenous retroviruses transcripts, but none of the other viruses, were detected in 15 out the 17 patients. Sequencing identified the virus as HERV-WE1 and E2. HERV-W activity was confirmed by high expression levels of syncytin, dsRNA, virus budding, and the presence of virus-like particles in all advanced osteoarthritis cartilages examined. Low levels of HERV-WE1, but not E2 envelope RNA, were observed in 3 out of 8 non-/early osteoarthritis patients, while only 3 out of 7 chondrocytes cultures displayed low levels of syncytin, and just one was positive for virus-like particles. This study demonstrates for the first time activation of HERV-W in cartilage of osteoarthritis patients; however, a causative role for HERV-W in development or deterioration of the disease remains to be proven.

Searching for foreign antigens as possible triggering factors of autoimmunity: Torque Teno virus DNA prevalence is elevated in sera of patients with bullous pemphigoid

OBJECTIVE

The Torque Teno virus (TTV), a member of virus genus Anellovirus has been shown to be commonly present in humans, yet without detectable pathogenicity. Recent studies imply that TTV may contribute to provoke autoimmune progresses in systemic lupus erythematosus and idiopathic inflammatory myopathies. We aimed to study the presence of TTV in a group of patients with autoimmune bullous diseases with a further goal to identify long-lasting foreign antigen, such as TTV as possible triggers of skin-specific autoimmunity.

PATIENTS AND METHODS

We performed in silico research to study similarities between known TTV sequences and antigens of bullous pemphigoid (BP), pemphigus vulgaris (PV) and dermatitis herpetiformis (DH). Basic Local Alignment Search Tool results showed matching regions for the major BP antigens BP180 and BP230, PV antigen desmoglein 3 and DH antigen transglutaminase 3 and disclosed overlapping, antigen-predicted sequences only for BP180 regions. We also assessed the prevalence of TTV in these disorders and compared them with the results from two healthy blood donor groups (group 1: sex- and age-matched for the general bullous group, n = 95; group 2: sex- and age-matched for BP, n = 50). Furthermore, we assayed lymphocytes from four TTV DNA and BP180 NC16A blot-positive BP patients and three controls in a standard lymphocyte transformation test with a TTV peptide from the conserved ORF(Open Reading Frame)1/N22 region.

RESULTS

We found that the detection rate of TTV was comparable with that in healthy controls in the group of PV (19/33); whereas detection rates in DH showed a slight, but not significant tendency for elevation (17/20). Contrary, the TTV prevalence in BP patients was significantly elevated (group 1: 36/40 vs group 2: 31/50, P < 0.032). Lymphocytes from all four virus-positive BP patients heavily reacted to TTV peptide while two of the three healthy controls have shown not to recognize the viral sequences. Only the TTV carrier healthy control had a minor reaction at lowest peptide concentration. The combined in silico, polymerse chain reaction and in vitro cell assay data of the present study indicate that a TTV persistence may contribute to the pathogenesis of BP.

Prevalence of transfusion transmitted virus (TTV) genotypes among HCC patients in Qaluobia governorate

Background

Transfusion Transmitted virus (TTV) is a novel single-stranded DNA virus that was identified in patients with post-transfusion hepatitis of non-A-G type. Clinical significance of TTV infection was analyzed in Egyptian hepatocellular carcinoma (HCC) patients. The present study attempted to clarify these issues in Egypt, particularly in Qaluobia governorate, a country known for its high endemicity of liver disease and hepatotropic viruses.

Methods

TTV are determined in the serum of 60 samples obtained from HCC and liver cirrhosis (LC) patients and 30 healthy individuals. TTV DNA is amplified by nested-PCR with TTV-specific mixed primers derived from the conserved open reading frame 1 (ORF1) region followed by digestion with restriction enzyme. Using the enzymes HaeIII, DraI, EcoRI and PstI, we are able to distinguish between the four TTV genotypes.

Results

The positive rate of TTV detection was 46.7%, 40% and 36.7% among HCC, LC patients and healthy individuals respectively. The more prevalence genotype was detected in the positive serum samples was genotype 1 (35.7%) in HCC patients, (50%) in LC and (63.3%) in healthy individuals, Genotype 5 (21.4%), (25.5%) and (18.2%) in HCC, LC and healthy individuals respectively.

Discussion

This study indicates that TTV is commonly present in adult patients with HCC and LC as well as healthy individuals. The most prevalence TTV genotype is genotype 1. It seems that the infection neither contribute to the severity of liver disease no to the causation of HCC.

Torque teno virus (SANBAN isolate) ORF2 protein suppresses NF-kappaB pathways via interaction with IkappaB kinases

Since the first discovery of Torque teno virus (TTV) in 1997, many researchers focused on its epidemiology and transcriptional regulation, but the function of TTV-encoded proteins remained unknown. The function of the TTV open reading frame (ORF) in the nuclear factor kappaB (NF-kappaB) pathway has not yet been established. In this study, we found for the first time that the TTV ORF2 protein could suppress NF-kappaB activity in a dose-dependent manner in the canonical NF-kappaB pathway. By Western blot analysis, we proved that the TTV ORF2 protein did not alter the level of NF-kappaB expression but prevented the p50 and p65 subunits from entering the nucleus due to the inhibition of IkappaBalpha protein degradation. Further immunoprecipitation assays showed that the TTV ORF2 protein could physically interact with IKKbeta as well as IKKalpha, but not IKKgamma. Luciferase assays and Western blot experiments showed that the TTV ORF2 protein could also suppress NF-kappaB activity in the noncanonical NF-kappaB pathway and block the activation and translocation of p52. Finally, we found that the TTV ORF2 protein inhibited the transcription of NF-kappaB-mediated downstream genes (interleukin 6 [IL-6], IL-8, and COX-2) through down-regulation of NF-kappaB. Together, these data indicate that the TTV ORF2 protein suppresses the canonical and noncanonical NF-kappaB pathways, suggesting that the TTV ORF2 protein may be involved in regulating the innate and adaptive immunity of organisms, contributing to TTV pathogenesis, and even be related to some diseases.

Possible pathogenic nature of the recently discovered TT virus: Does it play a role in autoimmune rheumatic diseases?

Pathogenesis of viral origin has long been suggested in autoimmune rheumatic diseases. Beside the well-defined virus induced transient or chronic rheumatic diseases often resembling systemic autoimmune disorders such as rheumatoid arthritis, viruses can contribute to disease pathogenesis by several different pathomechanisms. TT virus is a recently discovered virus of extremely high genetic diversity which commonly infects humans. Despite accumulated evidence on the biological characteristics of TTV, its pathogenicity is still in question; many consider TTV as a harmless endosymbiont. The recent paper overviews the biology of TT virus and investigates the hypothesis that TTV might have a causative role in human diseases with special attention to the possibility that TTV might trigger autoimmunity in rheumatic disorders.

Detection of TT Virus in Patients with Idiopathic Inflammatory Myopathies

The TT virus, a recently identified single-stranded DNA virus with unknown pathogenicity, has been shown to commonly infect humans. Viruses have been considered to contribute to disease pathogenesis in autoimmune disorders including idiopathic inflammatory myopathies (IIMs) and rheumatoid arthritis (RA). We assessed the prevalence of TTV infection in IIM compared with that in patients with RA and healthy blood donors. Detection of TTV was conducted by nested PCR and real-time PCR in the sera of 94 patients with IIM, 95 RA patients. and 95 age- and sex-matched healthy blood donors. Identity of the PCR products was confirmed by sequencing. TTV DNA was detected in 61 of 94 (64.9%) patients with IIM, in 64 of 95 (67.4%) patients with RA, and in 62 of 95 (65.3%; P > 0.05) healthy individuals. Age, sex, activity, or duration of disease had no influence on TTV positivity in either group. However, patients with severe IIM (n = 36) had a significantly higher rate of TTV infection (31/36, 86.1%) than patients with mild disease (30/58, 51.7%, P < 0.05, chi(2) = 10.0). Disease was considered severe in IIM when immunosuppressive treatment was necessary because of continuous high activity and/or serious inner-organ involvement despite corticosteroid treatment. In conclusion, although we found the detection rate of TTV similar in patients with idiopathic inflammatory myopathies and rheumatoid arthritis and comparable to that in healthy controls, our data suggest that infection with TT virus may result in a more severe disease in patients with idiopathic inflammatory myopathies.

The role of infectious agents in the pathogenesis of systemic sclerosis

Over the past few years, increasing evidence has accumulated to implicate infectious agents in the etiology of systemic sclerosis (SSc) and Raynaud phenomenon. Infection rates in patients with SSc compared with those in control populations do not provide clear support for any specific pathogen. However, increased antibody titers, a preponderance of specific strains in patients with SSc, and evidence of molecular mimicry inducing autoimmune responses suggest mechanisms by which infectious agents may contribute to the development and progression of SSc. Here we review studies examining the potential involvement of, cytomegalovirus, and parvovirus B19 in SSc pathogenesis.

Prevalence and genomic variability of transfusion transmitted virus in Italian cryptogenic chronic liver disease and healthy blood donors

BACKGROUND

Infection with transfusion transmitted virus, a new member of the Parvoviridae family, has been found in patients both with chronic and fulminant post-transfusion cryptogenic hepatitis.

AIM

To evaluate the prevalence and clinical impact of transfusion transmitted virus infection in Italy.

PATIENTS AND METHODS

Studies were carried out on 256 patients and control subjects from three centres from Northern, Central and Southern Italy (92 nonA-nonC chronic hepatitis, 10 acute non fulminant cryptogenic hepatitis, 41 hepatitis C virus-related chronic hepatitis and 113 blood donors). Serum transfusion transmitted virus was detected by nested polymerase chain reaction using two overlapping sets of primers.

RESULTS

A total of 52 of the 92 patients (54.3%) with chronic cryptogenic liver disease and 17 of the 41 hepatitis C virus chronic hepatitis patients (41.4%) were transfusion transmitted virus-DNA positive. Transfusion transmitted virus co-infection in hepatitis C virus patients was not associated with either a higher severity of liver histology or higher alanine transaminase levels or signs of cholestasis, transfusion transmitted virus was found in 48 out of 113 (42.4%) blood donors. In the majority of samples, transfusion transmitted virus DNA was detected with only one of the two sets of primers used. Genotyping and phylogenetic analysis performed on 21 randomly selected viral isolates showed the presence of both type 1 and type 2 transfusion transmitted virus and allowed identification of two isolates with high homology to genotype 6, described, so far, mostly in Japan.

CONCLUSIONS

Transfusion transmitted virus type 1 and 2 infection is common among blood donors and patients with liver disease in Italy. The pathogenic potential of transfusion transmitted virus type 1 and 2 in nonA-nonC hepatitis patients is unlikely but further studies are needed to evaluate the epidemiological and clinical impact of other transfusion transmitted virus subtypes.

Real-time PCR methods for independent quantitation of TTV and TLMV

There is considerable interest in the possible clinical effects of the human circoviruses TT virus (TTV) and TTV-like mini virus (TLMV). Most people appear to have at least one of these viruses replicating actively in their bodies, thus mere correlation of the presence of virus and disease states are probably less informative than a quantitative analysis of viraemia. Real-time PCR based methods, with either SYBR Green or TaqMan probe, designed to quantitate selectively TTV and TLMV are described. The suggested TaqMan-based protocols were suitable for quantitation of viruses in the range of 10(2)-10(9) copies/ml of sample; and proved, by sequencing of PCR products, to be specific for each of the two viruses.