TT virus DNA in serum, peripheral blood mononuclear cells and semen of patients infected by HIV

Human seminal virome: a panel based on recent literature

Background

The seminal virome and its implications for fertility remain poorly understood. To date, there are no defined panels for the detection of viruses of clinical interest in seminal samples.

Results

In this study, we characterized the human seminal virome based on more than 1,000 studies published over the last five years.

Conclusions

The number of studies investigating viruses that occur in human semen has increased, and to date, these studies have been mostly prospective or related to specific clinical findings. Through the joint analysis of all these studies, we have listed the viruses related to the worsening of seminal parameters and propose a new panel with the main viruses already described that possibly affect male fertility and health. This panel can assist in evaluating semen quality and serve as a tool for investigation in cases of infertility.

Viruses in the reproductive tract: On their way to the germ line?

Studies of vertebrate genomes have indicated that all species contain in their chromosomes stretches of DNA with sequence similarity to viral genomes. How such 'endogenous' viral elements (EVEs) ended up in host genomes is usually explained in general terms such as 'they entered the germ line at some point during evolution'. This seems a correct statement, but is also rather imprecise. The vast number of endogenous viral sequences suggest that common routes to the 'germ line' may exist, as relying on chance alone may not easily explain the abundance of EVEs in modern mammalian genomes. An increasing number of virus types have been detected in human semen and a growing number of studies have reported on viral infections that cause male infertility or subfertility and on viral infections that threaten in vitro fertilisation practices. Thus, it is timely to survey the pathway(s) that viruses can use to gain access to the human germ line. Embryo transfer and semen quality studies in livestock form another source of relevant information because virus infection during reproduction is clearly unwanted, as is the case for the human situation. In this review, studies on viruses in the male and female reproductive tract and in the early embryo will be discussed to propose a plausible viral route to the mammalian germ line.

Semen virome of men with HIV on or off antiretroviral treatment

OBJECTIVES

Improving immune status of people living with HIV through antiretroviral therapy (ART) may also reduce shedding of other viruses in semen. We characterized the seminal fluid virome of men with HIV and tested potential associations between viruses present and CD4 T-cell count, HIV viremia, and antiretroviral therapy (ART) status.

DESIGN AND METHODS

Metagenomics was used to enrich and sequence viral nucleic acids from the seminal fluid of 55 semen samples from 42 men living with HIV from San Francisco with a median age of 33 (IQR, 28.7-45) and median CD4 T-cell counts of 837 cells/μl (IQR, 258-1571 cells/μl). All samples were collected between 2005 and 2015, and ART status was ascertained from medical records.

RESULTS

Anelloviruses, cytomegalovirus (CMV), and multiple genotypes of human papillomaviruses were detected. Participants shed from 0 to 4 distinct human viruses. Longitudinally collected seminal fluid samples showed changes in the viruses shed. Viruses were more frequently shed by individuals with detectable HIV viremia (43.7 vs. 15.4%, P = 0.042). A trend was seen for increased shedding by individuals who were not on ART (42.8 vs. 17.8%, P = 0.082) or with CD4 T-cell count less than 350 cells/μl (35.3 vs. 20%, P = 0.27).

CONCLUSION

Seminal fluid from men with HIV from San Francisco contains nucleic acids from three different DNA viral families. A greater number of viruses, particularly CMV, were shed by participants with detectable HIV viremia (18.9 vs. 0%, P = 0.022). Control of viremia through ART may lower shedding of other viruses in semen in addition to HIV.

Detection and molecular characterization of Torque Teno Virus (TTV) in Uruguay

Torque Teno Virus (TTV), member of Anelloviridae family, is considered a worldwide distributed emergent virus and is currently classified into seven genogroups. Interestingly, the pathogenicity of TTV remains unclear. However, it has been constantly associated to hepatitis cases of unknown etiology (HUE) as well as extensively studied in concurrent infections with Hepatitis B Virus (HBV), Hepatitis C Virus (HCV) and Human Immunodeficiency Virus type 1 (HIV-1). In South America, TTV epidemiological data is scant, involving some studies from Brazil, Venezuela, Colombia and Bolivia. The aim of this work was to investigate for the first time in Uruguay the presence of TTV by a nested-PCR system in 85 human serum samples infected with HBV and/or HCV and/or HIV-1 and in HUE cases. Overall, our results reported a TTV infection rate of 79% (67/85). Furthermore, the molecular characterization of Uruguayan strains revealed that one of them clustered in genogroup 1, while the remaining ones formed separate clusters closely related to genogroup 3, which should be confirmed by complete genome sequencing. Further investigation about TTV circulation in Uruguayan population is needed in order to provide additional information about the genetic variability and TTV epidemiology in South America.

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.

TT virus prevalence, viral loads and genotypic variability in saliva from healthy Japanese children

AIM

TT virus (TTV) is genetically variable and widespread without apparent pathogenicity; however, its epidemiological features in children were not fully understood, partly because blood sampling is often unacceptable for healthy children. We therefore used saliva specimens to investigate epidemiology of TTV infection in early childhood.

METHODS

Saliva samples were collected from 83 1-month-old, 110 4-month-old and 49 42-month-old children. Peripheral blood mononuclear cells (PBMC) and saliva samples were obtained in pairs from 19 healthy adults aged 40 +/- 7 years. TTV DNA was detected and quantified by real-time PCR and classified into five genogroups (G1-G5) by a series of PCRs using genogroup-specific primer pairs.

RESULTS

TTV DNA was detected in 6, 34 and 90% of children aged 1, 4 and 42 months, respectively, and in 84% of adults. Comparable levels of TTV DNA were detected in pairs of saliva and PBMC. TTV loads in saliva were much higher in children than in adults. G3 was the most common genogroup in all age groups. The second most prevalent was G4 at 1-4 months of age and G1 thereafter.

CONCLUSION

The prevalence of TTV infection reached a plateau at or before 42 months; however, somehow different epidemiologic features were observed among genogroups.

Transfusion transmitted virus: A review on its molecular characteristics and role in medicine

The present review gives an updated overview of transfusion transmitted virus (TTV), a novel agent, in relation to its molecular characteristics, epidemiological features, modes of transmission, tissue tropism, pathogenesis, role in various diseases and its eradication from the body. TTV, a DNA virus, is a single stranded, non-enveloped, 3.8 kb long DNA virus with a small and covalently closed circular genome comprising 3852 bases. It was tentatively designated Circinoviridae virus. TTV genome sequence is heterogeneous and reveals the existence of six different genotypes and several subtypes. TTV has been reported to transmit not only via parenteral routes, but also via alternate routes. This virus has been detected in different non-human primates as well. At present, TTV is detected by polymerase chain reaction (PCR) with no other available diagnostic assays. It shows its presence globally and was detected in high percent populations of healthy persons as well as in various disease groups. Initially it was supposed to have strong association with liver disease; however, there is little evidence to show its liver tropism and contribution in causing liver diseases. It shows high prevalence in hemodialysis patients, pointing towards its significance in renal diseases. In addition, TTV is associated with several infectious and non-infectious diseases. Although its exact pathogenesis is not yet clear, TTV virus possibly resides and multiplies in bone marrow cells and peripheral blood mononuclear cells (PBMCs). Recently, attempts have been made to eradicate this virus with interferon treatment. More information is still needed to extricate various mysteries related to TTV.

[The novel non-A, non-E hepatitis viruses and their pathogenic effect]

Molecular techniques have allowed the identification of new viruses in a number of patients with cryptogenic hepatitis. Whether they are clinically inapparent or true hepatitis agents remains unknown for some of them. Latest described viruses include GBV, TTV and SENV. However, based on the limited data available, they do not seem to be contenders for the new hepatitis virus title. However, researchers are looking for a role of these viruses in other chronic and acute human diseases. Only a careful evaluation of the data and the scientific concordance of all the evidence will resolve the question of whether they are only commensal viruses or pose a real pathogenic potential.

TT virus is distributed in various leukocyte subpopulations at distinct levels, with the highest viral load in granulocytes

When TT virus (TTV) DNA was quantitated in whole blood and plasma aliquots from 27 viremic individuals by real-time detection PCR that can detect essentially all TTV genotypes, the TTV load was 6.9 +/- 3.5 (mean +/- standard deviation)-fold higher in the whole blood than in the plasma samples [P < 0.002 (paired t test)]. To clarify the reason for this difference, peripheral blood cells of various types including red blood cells, granulocytes (CD15+), B cells (CD19+), T cells (CD3+), monocytes (CD14+), and NK cells (CD3-/CD56+) were separated at a purity of 95.4-99.5% from each of three infected individuals with relatively high TTV viremia, and their TTV viral loads were determined. Red blood cells were uniformly negative, but the other cell types were positive for TTV DNA at various titers. In all three patients, the highest TTV load was found in granulocytes (4.2 x 10(4)-3.1 x 10(5) copies/10(6) cells), followed by monocytes (1.4-2.2 x 10(4) copies/10(6) cells) and NK cells (5.4-6.5 x 10(3) copies/10(6) cells); B and T cells were positive, with a low viral load (6.7 x 10(1)-2.7 x 10(3) copies/10(6) cells). These results indicate that TTV is distributed in various peripheral blood cell types at distinct levels, with the highest viral load in granulocytes, and that a significant proportion of the TTV DNA in peripheral blood is not identified by the standard plasma/serum DNA detection methods.