Prevalence of occult hepatitis B virus infection and Torque teno virus infection and their association with hepatocellular carcinoma in chronic hepatitis C patients

Torque Teno Virus (TTV) in Renal Transplant Recipients: Species Diversity and Variability

Torque Teno Virus (TTV) is a nonpathogenic and ubiquitous ssDNA virus, a member of the Anelloviridae family. TTV has been postulated as a biomarker in transplant patients. This study aimed to determine the TTV species diversity and variability in renal transplant recipients and to associate species diversity with the corresponding TTV viral load. From 27 recipients, 30 plasma samples were selected. Viral load was determined using two real-time PCR assays, followed by RCA-NGS and ORF1 phylogenetic analysis. The TTV diversity was determined in all samples. Variability was determined in three patients with two sequential samples (pre- and post-transplantation). Most of the samples presented multiple TTV species, up to 15 different species were detected. In the pre-transplant samples (n = 12), the most prevalent species were TTV3 (75%) and TTV13 (75%), and the median number of species per sample was 5 (IQR: 4-7.5). TTV3 was also the most prevalent (56%) in the post-transplant samples (n = 18), and the median number of species was 2 (IQR: 1.8-5.5). No significant correlation between the number of species and viral load was found. The number and type of TTV species showed total variability over time. We report high TTV species diversity in Argentinian recipients, especially in pre-transplant period, with total intra-host variability. However, we found no significant correlation between this high diversity and TTV viral load.

The mysterious anelloviruses: investigating its role in human diseases

Anelloviruses (AVs) that infect the human population are members of the Anelloviridae family. They are widely distributed in human populations worldwide. Torque teno virus (TTV) was the first virus of this family to be identified and is estimated to be found in the serum of 80-90% of the human population. Sometime after the identification of TTV, Torque teno mini virus (TTMV) and Torque teno midi virus (TTMDV) were also identified and classified in this family. Since identifying these viruses, have been detected in various types of biological fluids of the human body, including blood and urine, as well as vital organs such as the liver and kidney. They can be transmitted from person to person through blood transfusions, fecal-oral contact, and possibly sexual intercourse. Recent studies on these newly introduced viruses show that although they are not directly related to human disease, they may be indirectly involved in initiating or exacerbating some human population-related diseases and viral infections. Among these diseases, we can mention various types of cancers, immune system diseases, viral infections, hepatitis, and AIDS. Also, they likely use the microRNAs (miRNAs) they encode to fulfill this cooperative role. Also, in recent years, the role of proliferation and their viral load, especially TTV, has been highlighted to indicate the immune system status of immunocompromised people or people who undergo organ transplants. Here, we review the possible role of these viruses in diseases that target humans and highlight them as important viruses that require further study. This review can provide new insights to researchers.

Torque teno virus and cancers: current knowledge

Aim: The aim of this systematic review is to assess the current knowledge about the relationship between Torque teno virus (TTV) and cancer in different settings. Methods: A systematic search was conducted in Medline via PubMed, Embase and Cochrane Library from the inception to the end of January 2023. Results: 34 articles were included in the qualitative synthesis of this review and 2145 patients with solid tumors have been analyzed. The most prevalent cancer types were hepatocellular carcinoma (HCC) and lung cancer. Conclusion: TTV has proven its role as a marker of functional immune competence in the setting of hematopoietic stem cell transplantation (HSCT), but in the oncological field is yet to be defined.

Phylogenetic analysis of torque teno virus in Romania: possible evidence of distinct geographical distribution

Torque teno virus (TTV) is highly prevalent, but little is known about its circulation in humans. Here, we investigated the geographical distribution and phylogeny of TTV in Romania. A fragment of TTV untranslated region B was sequenced in samples from volunteers across the country. Additional sequences from dialyzed patients were also included in the study. Phylogenetic analysis showed that more than 80% of Romanian sequences clustered with isolates assigned to the species Torque teno virus 1 and Torque teno virus 3 (former genogroup 1), and this analysis discriminated between isolates from the North-East and West regions. Further studies assessing the pathogenic potential of TTV isolates should employ analysis based on genomic regions with phylogenetic resolution below the species level.

Occult hepatitis B virus infection in patients with chronic liver disease of different etiology in a Brazilian referral center: comparison of two different hepatitis B virus deoxyribonucleic acid amplification protocols: a cross-sectional study

BACKGROUND

Occult hepatitis B virus infection (OBI) is defined as the presence of hepatitis B virus (HBV) deoxyribonucleic acid (DNA) in the liver of individuals with undetectable hepatitis B virus surface antigen (HBsAg) in the serum. The actual prevalence of OBI and its clinical relevance are not yet fully understood.

OBJECTIVE

To evaluate the prevalence of HBV DNA in liver biopsies of HBsAg-negative patients with chronic liver disease of different etiologies in a referral center in Brazil and compare two different HBV DNA amplification protocols to detect HBV.

DESIGN AND SETTING

This cross-sectional observational study was conducted at the Liver Outpatient Clinic, Hospital das Clínicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil, between January 2016 and December 2019.

METHODS

HBV DNA was investigated in 104 liver biopsy samples from individuals with chronic liver disease of different etiologies, in whom HBsAg was undetectable in serum by nested-polymerase chain reaction (nested-PCR), using two different protocols.

RESULTS

OBI, diagnosed by detecting HBV DNA using both protocols, was detected in 6.7% of the 104 individuals investigated. Both protocols showed a good reliability.

CONCLUSION

In addition to the differences in the prevalence of HBV infection in different regions, variations in the polymerase chain reaction technique used for HBV DNA amplification may be responsible for the large variations in the prevalence of OBI identified in different studies. There is a need for better standardization of the diagnostic methods used to diagnose this entity.

Cytokine profile during occult hepatitis B virus infection in chronic hepatitis C patients

Background

The hepatitis B virus (HBV) is one of the leading causes of acute, chronic and occult hepatitis (OBI) representing a serious public health threat. Cytokines are known to be important chemical mediators that regulate the differentiation, proliferation and function of immune cells. Accumulating evidence indicate that the inadequate immune responses are responsible for HBV persistency. The aim of this study were to investigate the cytokines IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10 and IL-17A in patients with OBI and verify if there is an association between the levels of these cytokines with the determination of clinical courses during HBV occult infection.

Methods

114 patients with chronic hepatitis C were investigated through serological and molecular tests, the OBI coinfected patients were subjected to the test for cytokines using the commercial human CBA kit. As controls, ten healthy donors with no history of liver disease and 10 chronic HBV monoinfected patients of similar age to OBI patients were selected.

Results

Among 114 HCV patients investigated, 11 individuals had occult hepatitis B. The levels of cytokines were heterogeneous between the groups, most of the cytokines showed higher levels of production detection among OBI/HCV individuals when compared to control group and HBV monoinfected pacients. We found a high level of IL-17A in the HBV monoinfected group, high levels of TNF-α, IL-10, IL-6, IL-4 and IL-2 in OBI/HCV patients.

Conclusion

These cytokines could be involved in the persistence of HBV DNA in hepatocytes triggers a constant immune response, inducing continuous liver inflammation, which can accelerate liver damage and favor the development of liver cirrhosis in other chronic liver diseases.

Frequency of OBI among Patients with Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is recognized as a serious disease in which the body’s immune system attacks liver cells so untreated patients may consequently suffer from liver cirrhosis, hepatocellular carcinoma (HCC) and liver failure. The role of viral infection may be involved in AIH. Presence of anti-HBc alone is a predictive signal of potential OBI. Thus, this study was conducted to evaluate the rate OBI among the patients with AIH.

Torque teno virus in liver diseases: On the way towards unity of view

The review presents the data accumulated for more than 20 years of research of torque teno virus (TTV). Its molecular genetic structure, immunobiology, epidemiology, diagnostic methods, possible replication sites, and pathogenicity factors are described. TTV is a virus that is frequently detectable in patients with different viral hepatitides, in cases of hepatitis without an obvious viral agent, as well as in a healthy population. There is evidence suggesting that biochemical and histological changes occur in liver tissue and bile duct epithelium in TTV monoinfection. There are sufficient histological signs of liver damage, which confirm that the virus can undergo a replicative cycle in hepatocytes. Along with this, cytological hybridization in TTV-infected cells has shown no substantial cytopathic (cell-damaging) effects that are characteristic of pathogenic hepatotropic viruses. Studying TTV has led to the evolution of views on its role in the development of human pathology. The first ideas about the hepatotropism of the virus were gradually reformed as new data became available on the prevalence of the virus and its co-infection with other viruses, including the viruses of the known types of hepatitides. The high prevalence of TTV in the human population indicates its persistence in the body as a virome and a non-pathogenic virus. It has recently been proposed that the level of TTV DNA in the blood of patients undergoing organ transplantation should be used as an endogenous marker of the body’s immune status. The available data show the polytropism of the virus and deny the fact that TTV can be assigned exclusively to hepatitis viruses. Fortunately, the rare detection of the damaging effect of TTV on hepatic and bile duct epithelial cells may be indirect evidence of its conditionally pathogenic properties. The ubiquity of the virus and the variability of its existence in humans cannot put an end to its study.

Prevalence of torque teno virus in healthy individuals and those infected with hepatitis C virus living in Yazd, Iran

BACKGROUND

Torque teno virus (TTV) is a non-enveloped DNA virus that its role as a helper or causative agent in hepatitis is still unclear. TTV prevalence varies in different regions of the world. This study aimed to determine the prevalence of TTV in healthy individuals and those infected with hepatitis C virus (HCV) living in Yazd city, Iran.

METHODS

In this case-control study, 50 healthy subjects and 68 HCV-positive individuals who referred to Yazd hospitals participated in this study. TTV DNA in serum samples were detected by nested polymerase chain reaction (PCR) using specific primers of 5΄-UTR and N22 regions. The genotypes of HCV and TTV were determined by sequencing method.

RESULTS

TTV-DNA was detected in 2 out of 50 (4℅) healthy individuals and in 4 out of 68 (5.8℅) HCV-positive persons. There was not a significant correlation between the prevalence of TTV and HCV infection. The most common TTV genotypes among HCV-positive individuals were 3, 17 and 13, respectively. There was not a significant association obtained between HCV genotypes and TTV genotypes.

CONCLUSION

The prevalence of TTV in Yazd province was low compared with the other areas of Iran. The prevalence of TTV in HCV infected people was not significantly higher than its rate in uninfected individuals.

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.

The Role of Emerging and Neglected Viruses in the Etiology of Hepatitis

PURPOSE OF REVIEW

In this review, we present the overview of emerging and neglected viruses associated with liver involvement.

RECENT FINDINGS

Hepatitis E virus (HEV) emerged in the last two decades, causing hepatitis in many parts of the world. Moreover, liver involvement was also described in some emerging arboviral infections. Many reports showed dengue-associated liver injury; however, chikungunya, West Nile, tick-borne encephalitis, and Zika virus are rarely associated with clinically manifest liver disease. In addition, some neglected highly prevalent viruses such as adenoviruses and parvovirus B19 are capable of causing hepatitis in specific population groups. Anelloviruses (torque teno virus/torque teno mini virus/torque teno midi virus, SEN virus), human bocavirus, pegiviruses, and lymphocytic choriomeningitis virus have shown a little potential for causing hepatitis, but their role in the etiology of liver disease remains to be determined. In addition to the well-known hepatotropic viruses, many emerging and neglected viruses have been associated with liver diseases. The number of emerging zoonotic viruses has been increasingly recognized. While zoonotic potential of HEV is well documented, the recent identification of new hepatitis-related animal viruses such as HEV strains from rabbits and camels, non-primate hepaciviruses in domestic dogs and horses, as well as equine and porcine pegivirus highlights the possible zoonotic transmission in the context of "One Health." However, zoonotic potential and hepatotropism of animal hepatitis viruses remain to be determined.

Torquetenovirus (TTV) load is associated with mortality in Italian elderly subjects

An age-related dysregulation of immune response, known as immunosenescence, contributes to increased susceptibility to infections, frailty and high risk of mortality in the elderly. Torquetenovirus (TTV), a circular, single-stranded DNA virus, is highly prevalent in the general population and it may persist in the organism, also in association with other viruses such as cytomegalovirus (CMV), causing chronic viremia. The relationship that TTV establishes with the immune system of infected hosts is not clear. It is known that TTV encodes microRNAs (miRNAs) that might contribute to immune evasion and that the highest viral loads are found in peripheral blood cells. Moreover, it is suspected that TTV infection lead to increased production of inflammatory mediators, thus playing a role in immunosenescence. We investigated the association of TTV load and miRNAs expression with inflammatory and immune markers and the influence of TTV load on mortality within a cohort of 379 elderly subjects who were followed up for 3 years. TTV DNA load in polymorphonuclear leukocytes was slightly positively correlated with age and negatively associated with serum albumin levels and NK cell activity. A marginal positive correlation between TTV DNA load, monocytes and IL-8 plasma levels was found in females and males respectively. TTV DNA copies ≥4.0 log represented a strong predictor of mortality (Hazard ratio = 4.78, 95% CI: 1.70-13.44, after adjusting for age, sex and the main predictors of mortality rate) and this association remained significant even after the CMV IgG antibody titer was included in the model (HR = 9.83; 95% CI: 2.48-38.97; N = 343 subjects). Moreover, multiple linear regression model showed that TTV miRNA-t3b of genogroup 3 was inversely associated with triglycerides, monocytes and C-reactive protein, and directly associated with IL6. Overall these findings suggest a role of TTV in immunesenescence and in the prediction of all-cause mortality risk in Italian elderly subjects. Further studies are needed to fully understand the pathogenic mechanisms of TTV infection during aging.