Clinical significance of TT virus infection in children with chronic hepatitis B

Multiple genotypes infection and molecular characterization of Torque teno neovison virus: A novel Anelloviridae of mink in China

A novel Torque teno neovison virus (TTVs) was identified in specimens collected from dead mink during an outbreak of the Aleutian mink disease virus. Eighteen complete genomic sequences were obtained, ranging from 2109 to 2158 nucleotides in length and consisting of an untranslated region and three open reading frames. The genomic organization of mink TTVs is similar to previously reported anelloviruses. However, the deduced amino acid sequence of its ORF1 protein shows genetic diversity compared to related anelloviruses, suggesting that it represents a putative new species within the Anelloviridae family. This study provides a detailed molecular characterization of the novel mink anelloviruses, including its codon usage pattern, origin, and evolution. Analysis of the viral genomic sequences reveals the existence of multiple genotypes of co-infection. Principal component analysis and phylogenetic trees confirm the coexistence of multiple genotypes. Furthermore, the codon usage analyses indicate that mink TTVs have a genotype-specific codon usage pattern and show a low codon usage bias. Host-specific adaptation analysis suggests that TTVs are less adapted to mink. The possible origin and evolutionary history of mink TTVs were elucidated. Mink TTVs was genetically closely related to giant panda anellovirus, representing a new species. The observed incongruence between the phylogenetic history of TTVs and that of their hosts suggests that the evolution of anellovirus is largely determined by cross-species transmission. The study provides insights into the co-infection and genetic evolution of anellovirus in China.

Torque Teno Sus Virus (TTSuV) Prevalence in Wild Fauna of Northern Italy

Torque teno sus virus (TTSuV) is a non-enveloped circular ssDNA virus which frequently infects swine and has been associated with hepatic, respiratory, and autoimmune disorders. TTSuV’s pathogenic role is still uncertain, and clear data in the literature on virus reservoirs are lacking. The aims of this study were to investigate the presence of potentially zoonotic TTSuV in wild animals in Northern Italy and to evaluate their role as reservoirs. Liver samples were collected between 2016 and 2020 during four hunting seasons from wild boars (Sus scrofa), red deer (Cervus elaphus), roe deer (Capreolus capreolus), and chamois (Rupicapra rupicapra). Samples originated from areas in Northern Italy characterized by different traits, i.e., mountains and flatland with, respectively low and high farm density and anthropization. Viral identification was carried out by end-point PCR with specific primers for TTSuV1a and TTSuVk2a species. TTSuV prevalence in wild boars was higher in the mountains than in the flatland (prevalence of 6.2% and 2.3%, respectively). In wild ruminants only TTSuVk2a was detected (with a prevalence of 9.4%). Our findings shed light on the occurrence and distribution of TTSuV in some wild animal species, investigating their possible role as reservoirs.

Hepatitis B Virus Molecular Epidemiology, Host-Virus Interaction, Coinfection, and Laboratory Diagnosis in the MENA Region: An Update

Hepatitis B virus (HBV) is an enveloped partial double-stranded DNA virus that can cause acute and chronic hepatitis. According to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), 257 million people are living with HBV. Moreover, 20,900 acute hepatitis B cases were reported in 2016. Hepatitis B is highly prevalent in the African, Western Pacific, Eastern Mediterranean, South-East Asia, and European regions, respectively. Due to the high mutational rate of HBV and lack of reverse transcriptase proofreading activity, ten different genotypes with different geographical distributions have been identified. HBV pathogenesis and severity of infection depend on several host and viral factors, particularly, the genetic variability of both the host and virus. Although HBV infection is a global health concern, there is a lack of adequate studies and reports in the Middle East and North Africa (MENA) region. Here, we provide a review on HBV epidemiology, pathogenesis, host-pathogen interactions, coinfection with selected viruses, and laboratory diagnosis, focusing on studies conducted in the MENA region to determine the current situation of the HBV infection and outline the future study areas.

Detection of Torque Teno Sus Virus in Pork Bile and Liver Sausages

Torque teno viruses (TTV) are small DNA viruses widespread among humans and pigs. The clinical significance of TTV infections in either humans or pigs is uncertain. In fact, TTV viremia is highly prevalent in patients with different pathologies, but it can also be frequently observed in healthy subjects. Virus infection in pigs is considered a putative cofactor in several diseases; despite being detected frequently in healthy animals, its role still remains unknown. The present study aimed to investigate the presence of Torque teno sus virus (TTSuV) in 62 bile samples collected from pigs at slaughterhouse and in 36 fresh pork liver sausages bought at point of sale. Quantitative Real-Time PCR, confirmed that 19.4 and 58.3 % of bile and sausage samples tested positive for TTSuV, respectively. The mean viral load was established as 5.6 × 10⁴ GE/µl for bile and 7.16 × 10³ GE/g for sausages. TTSuV nucleotide sequence analysis confirmed a wide heterogeneity among the circulating TTSuV strains, which included both TTSuV1 and TTSuV2.

Incidence and clinical implication of TT virus in patients with hepatitis and its frequency in blood donors in India

BACKGROUND

Transfusion Transmitted Virus (TTV), also known as Torque Teno Virus is a new novel viral agent which appears to correlate with some acute and chronic hepatitis cases and may produce liver damage under specific circumstances. Aim of this study was to detect TT virus by real-time PCR, study its clinical implications and effects of its co-infection in HBV and HCV chronic liver diseases.

METHODS

The study population comprised 50 acute hepatitis, 50 chronic hepatitis patients and 100 voluntary blood donors. All samples were tested for serum bilirubin, AST, ALT and alkaline phosphatase levels and for all available viral markers for hepatitis. The detection of TT viral genome was carried out by real-time PCR using TTV sequences as reported by Takahashi et al with modifications on the basis of database of the DDBJ/EMBL/GenBank (GenBank accession no. AB008394).

RESULT

Serum was positive for TTV in 72% of volunteer blood donors, 77.4% (24/31) of hepatitis A cases, 87.6% (36/41) of HBV-positive, 77% (10/13) of HCV-positive, and 92.8% (13/14) of non-B, non-C cases. Co-infection of TTV with other hepatitis viruses was detected in some patients.

CONCLUSION

TTV is a frequent virus detected in patients with various types of viral hepatitis, in cases of hepatitis without obvious viral agent, and from the healthy population in India. Rate of TTV was found to be significantly higher (92.8%) for Non A-E hepatitis group.

Phylogenetic analysis of Torque Teno Virus genome from Pakistani isolate and incidence of co-infection among HBV/HCV infected patients

BACKGROUND

Torque Teno Virus (TTV) was the first single stranded circular DNA virus to be discovered that infects humans. Although there have been numerous reports regarding the prevalence of TTV from other countries of South Asia, there is severe lack of information regarding its prevalence in Pakistan. Thus the present study compiles the first indigenous report to comprehensively illustrate the incidence of the virus in uninfected and hepatitis infected population from Pakistan. Another aim of the study was to present the sequence of full length TTV genome from a local isolate and compare it with the already reported genome sequences from other parts of the world.

METHODS

TTV DNA was screened in the serum of 116, 100 and 40 HBV infected, HCV infected and uninfected individuals respectively. Nearly full length genome of TTV was cloned from a HBV patient. The genome sequence was subjected to in-silico analysis using CLC Workbench, ClustalW, ClustalX and TreeView. Statistical analysis was carried out in SPSS v17.0.

RESULTS

Our results report that 89.7%, 90.0% and 92.5% of HBV, HCV patients and healthy control population were positive for TTV infection. TTV genome of 3603 bp was also cloned from a local isolate and given the identity of TPK01. The TTV genome sequence mentioned in this paper is submitted in the GenBank/EMBL/DDBJ under the accession number JN980171. Phylogenetic analysis of TPK01 revealed that the Pakistani isolate has sequence similarities with genotype 23 and 22 (Genogroup 2).

CONCLUSION

The results of the current study indicate that the high frequency of TTV viremia in Pakistan conforms to the reports from other areas of the world, wherever screening of TTV DNA was performed against 5'-UTR of the genome. The high sequence diversity among TTV genome sequences and the high frequency of prevalence makes it harder to study this virus in cellular systems.

Torque teno sus virus in pigs: an emerging pathogen?

The newly established family Anelloviridae includes a number of viruses infecting humans (Torque teno viruses) and other animal species. The ones infecting domestic swine and wild boar are nowadays named Torque teno sus viruses (TTSuV), which are small circular single-stranded DNA viruses highly prevalent in the pig population. So far, two genetically distinct TTSuV species are infecting swine. Both TTSuVs appear to efficiently spread by vertical and horizontal transmission routes; in fact, foetuses may be infected and the prevalence and viral loads increase by age of the animals. Detailed immunological studies on TTSuVs are still lacking, but it seems that there are no efficient immunological responses limiting viraemia. These viruses are currently receiving more attention due to the latest results on disease association. Torque teno sus viruses have been circulating unnoticed in pigs for a long time, and even considered non-pathogenic by themselves; there is increasing evidence that points to influence the development of some diseases or even affect their outcome. Such link has been mainly established with porcine circovirus diseases.

Molecular detection of Torque teno virus in different breeds of swine

BACKGROUND

Torque teno virus (TTV), of the Anelloviridae family, Iotatorquevirus genus, is a non-enveloped, single-stranded, and negative sense DNA (ssDNA) virus infecting human and many domestic animals including swines. Very little information is known about the investigations of TTV prevalence in different swine breeds so far.

METHODS

In this study, 208 serum samples collected from seven swine breeds (Rongchang pig, Chenghua pig, Zibet pig, Wild boar, Duroc, Landrace, Large Yorkshire) from two independent farms were detected to determine the prevalence of two swine TTV genogroups, TTV1 and TTV 2, by nested polymerase chain reaction methods, and to analyse prevalence difference among these breeds.

RESULTS

The results showed that the prevalence of TTV in the seven breeds was 92%-100%. No significant difference (p > 0.05) in TTV infection was observed between different breeds. Interestingly, significantly higher prevalence for TTV1 in Rongchang boars (90%) and for TTV2 in Rongchang sows (95%) were detected, while co-infection rate (43.8%) was lower than other breeds. Sequence analysis showed that the homology of TTV1 and TTV2 were over 90.9% and 86.4% in these breeds, respectively.

CONCLUSIONS

The results indicated that TTV was widely distributed in the seven swine breeds. The prevalence of both TTV genogroups associated with swine breeds and genders. This study also respented the first description of swine TTV prevalence in different swine breeds. It was vitally necessary to further study swine TTV pathogenicity.

Sequence analysis of a Torque teno canis virus isolated in China

In the present study, a total of 158 fecal samples were collected from diarrheal dogs younger than 1 year old in pet clinic in China. 20 specimens (20/158, 13%) were positive for Torque teno canis virus DNA using detection PCR. One representative positive isolate designated LDL was randomly selected, cloned and sequenced. The complete genome of the LDL Chinese strain was 2799 nucleotides in length and contains three open reading frames (ORFs), which encode 576 (ORF1), 101 (ORF2), and 243 (ORF3) aa. Compared with the human and other animal TTV genomes, the genome of the LDL strain is clearly smaller and shares 95% identity with Japanese cf-TTV10 strain (AB076002). Phylogenetic analysis showed that the present Chinese Torque teno canis virus LDL strain was also closely clustered with the previous Japanese cf-TTV10 strain, and formed a different branch together with Torque teno sus viruses 1 and 2 compared with other Torque teno viruses, Torque teno mini virus, and Torque teno midi virus. Our study demonstrated that Torque teno canis virus is present in China.

Torque teno mini virus infection and multiple sclerosis

Multiple sclerosis (MS) is a disease of young adults which is characterized by autoimmune demyelination of the central nervous system. Interaction of genetics and environmental factors are required to cause MS. Among the proposed environmental factors for MS, viral infections are thought to play a role in the pathogenesis of the disease. Torque teno mini virus (TTMV), which has recently been shown to infect humans, is a member of circoviridae, and has a circular DNA with 2860 nucleotides. Since there are a few data about the pathogenicity of this virus, this study sought to investigate the presence of TTMV in sera from MS patients and healthy individuals. We studied 149 serum samples from MS patients and 150 sera of healthy individuals. Serum DNA was extracted using phenol-chloroform and was subjected to nested polymerase chain reaction. TTMV-DNA was detected in 24 (16%) sera of the healthy blood donors and in 21 (14.1%) samples of the MS patients, where the difference did not reach significance (p > .05). The result of this study could not establish an association between TTMV infection and MS.

Testing for viral contaminants of veterinary vaccines in Hungary

The safety of veterinary vaccines is of paramount importance and it is significantly jeopardised by extraneous agents such as bacteria, mycoplasma, Chlamydia and viruses. Several critical steps of vaccine manufacture involve a potential risk of viral contamination. Viruses, as extraneous, agents can be divided into two main groups. Group 1 agents, such as Pestivirus, chicken anaemia virus (CAV), and egg drop syndrome virus (EDSV) are well-known to manufacturers and authorities. Compendial detection methods, clear guidelines and legislation have been established to minimise the risk of contamination with these agents. Contrary to group 1, group 2 agents like Torque Teno virus (TTV) or RD114, a replication-competent feline γ-retrovirus, have only recently been recognised and their role as contaminants needs further investigation.

Randomly selected veterinary vaccines used between 1992 and 2009 were tested by nucleic acid amplification for CAV, EDSV, and TTV. Pestivirus contamination was examined in 33 vaccines used between 1996 and 2006 and a further 27 vaccines used between 2007 and 2009 based on random selection of these vaccines. In addition to random tests done on vaccines used from 2007 on, 12 batches of live Aujeszky's disease vaccines submitted to our laboratory for Official Control Authority Batch Release (OCABR) were also tested for Pestivirus.

Swine torque teno virus detection in pig commercial vaccines, enzymes for laboratory use and human drugs containing components of porcine origin

Torque teno viruses (TTVs) are vertebrate infecting, single-stranded circular DNA viruses. Two genetically distinct TTV genogroups (TTV1 and TTV2) infect swine worldwide with high prevalence. Currently, swine TTVs are considered non-pathogenic, although TTV2 has been linked to post-weaning multisystemic wasting syndrome, a porcine circovirus disease. On the other hand, pig materials are an important source of components used in porcine vaccine manufacturing, human drugs and commercial enzyme products. However, there is little information about the possible existence of extraneous viruses in products containing porcine-derived components. In the present study, 26 commercial swine vaccines, seven human drugs and three enzyme products from porcine origin were tested for the presence of TTV1 and TTV2 genomes by PCR. Four vaccines against Mycoplasma hyopneumoniae were positive for TTV2 by PCR. Three M. hyopneumoniae, one porcine parvovirus and one porcine reproductive and respiratory syndrome virus vaccines were PCR positive for TTV1. One human drug contained TTV1 DNA as well as a trypsin enzyme; a porcine-derived elastase product was positive for both TTV genogroups. These results show that swine TTVs are contaminants not only of swine vaccines but also of human drugs containing porcine components and enzymes for laboratory use.

Unraveling the puzzle of human anellovirus infections by comparison with avian infections with the chicken anemia virus

Current clinical studies on human annelloviruses infections are directed towards finding an associated disease. In this review we have emphasized the many similarities between human anellovirus and avian circoviruses and the cell and tissue types infected by these pathogens. We have done this in order to explore whether knowledge acquired from natural and experimental avian infections could reflect and be extrapolated to the less well-characterized human annellovirus infections. The knowledge gained from the avian system may provide suggestions for decoding the enigmatic human anellovirus infections, and finding the specific disease or diseases caused by these human anellovirus infections. Each additional parallelism between chicken anemia virus (CAV) and Torque teno virus (TTV) further strengthens this premise. As we have seen information from human infections can also be used to better understand avian infections as well. Increased attention must be focused on the "hidden" or unrecognized, seemingly asymptomatic effects of circovirus and anellovirus infections. Understanding the facilitating effect of these infections on disease progression caused by other pathogens may help to explain differences in outcome of complicated poultry and human diseases. The final course of a pathogenic infection is determined by variations in the state of health of the host before, during and after contact with a pathogen, in addition to the phenotype of the pathogen and host. The health burden of circoviridae and anellovirus infections may be underestimated, due to lack of awareness of the need to search past the predominant clinical effect of identified pathogens and look for modulation of cellular-based immunity caused by co-infecting circoviruses, and by analogy, human anneloviruses.

Transfusion-transmitted virus DNA in serum, tear and aqueous humour of patients undergoing cataract operation

PURPOSE

Transfusion-transmitted virus (TTV) is a novel non-enveloped, single-stranded DNA virus with unclear pathogenesis throughout the world. Many studies were conducted to determine this virus in various body fluids and different primer sets have been tested for accurate diagnosis. This study aimed to collect data on the prevalence of TTV in serum, tear and aqueous humour of patients undergoing planned cataract surgery and to determine efficacy of three different polymerase chain reaction (PCR) techniques.

METHODS

A total of 72 specimens (24 each of serum, tear and aqueous humour specimens) were collected from 24 patients (11 male and 13 female) having age-related cataract. The patients did not have any other ocular pathology. TTV DNA was investigated by three different PCR methods: a seminested PCR performed with Okamato's primers, a one-step PCR performed with degenerative Takashi's primers and a commercial real-time PCR system.

RESULTS

TTV DNA was detected in 20 (83.3%) of the 24 serum specimens by the one-step PCR and real-time PCR system. However, seminested PCR yielded a positivity rate of 25%. TTV DNA positivities of the one-step PCR and the real-time PCR system were 33.3% and 66.6% of the 24 tear specimens, respectively. Seminested PCR did not yield positive result in these specimens. From aqueous humour specimens, TTV DNA was detected in 3 (12.5%) of the 24 specimens only by the real-time PCR. TTV DNA positivity of seminested PCR was significantly low in all specimens.

CONCLUSIONS

TTV DNA was detected in serum, tear and aqueous humour of patients undergoing cataract surgery, supporting the idea that this virus can be detected almost all of the body fluids but at different rates under various PCR conditions and primer sets. Using commercial real-time PCR significantly increased the TTV DNA positivity.

Molecular detection of bovine and porcine Torque teno virus in plasma and feces

Torque teno virus (TTV) is frequently detected in humans, livestock and some companion animals. Very little is known about presence of TTV in Canadian livestock and the goal of this study was to evaluate the presence of TTV in swine and cattle using molecular tools. TTV DNA was detected and confirmed by sequencing in the plasma of 90.5% and in the feces of 60.3% of the animals tested in a single swine herd as well as 80.9% and 1.1% in the plasma of individuals from general Quebec swine and cattle populations, respectively. The impact of the TTV presence in livestock population for the agri-food chain should be further investigated.

Torque teno virus (TTV): current status

Torque teno virus (TTV), currently classified into the family Circoviridae, genus Anellovirus, was first found in a patient with non-A-E hepatitis. TTV has a single stranded circular DNA of approximately 3.8 kb. TTVs are extraordinarily diverse, spanning five groups including SANBAN and SEN viruses. Torque teno mini virus (TTMV) with approximately 2.9 kb genome also has wide variants. Recently, two related 2.2- and 2.6-kb species joined this community. Recombinations between variants are frequent. This extensive TTV diversity remains unexplained; it is unclear how TTVs could be viable, and why they require such genetic variation. An unequivocal culture system is still not available. TTVs are ubiquitous in > 90% of adults worldwide but no human pathogenicity of TTV has been fully established. Epidemiological surveys need to specify the variants being studied and clinical targets, and must calibrate the sensitivity of the assay used. Potentially interesting observations include a higher viral load in patients with severe idiopathic inflammatory myopathies, cancer and lupus. Active replication was also found in infants with acute respiratory diseases. TTV/TTMV-related viruses were found in chimpanzees, apes, African monkeys and tupaias, and also in chickens, pigs, cows, sheep and dogs. Experimentally, rhesus monkeys were persistently infected by TTV, but only 1/53 chimpanzees. TTV transcribes three species of mRNAs, 3.0-, 1.2- and 1.0-kb in the ratio of 60:5:35. Recently, at least three mRNAs were shown in chicken anaemia virus. The genomic region -154/-76 contains a critical promoter. TTV seems to have at least three proteins; however, the definite functions of these proteins await further research work.

Molecular detection of transfusion transmitted virus coinfection with some hepatotropic viruses

CONTEXT

A novel human DNA virus was isolated from the serum of a patient with posttransfusion hepatitis; it was named transfusion transmitted virus (TTV).

OBJECTIVE

To ascertain the influence of TTV (detected by polymerase chain reaction amplification of a conserved region of the viral genome) coinfection in individuals infected with hepatitis viruses (A, B, and C) and to investigate the putative role played by TTV in hepatic dysfunction in individuals with acute non-A-E hepatitis.

DESIGN

Sixty-two patients with viral hepatitis were included in the study in addition to 18 blood donors. Viral study of 4 hepatotropic viruses (A, B, C, and E) was carried out. Study for TTV DNA was performed by nested polymerase chain reaction.

RESULTS

The prevalence of TTV was not statistically different between hepatitis patients and blood donors, and it was not correlated to the levels of the hepatic aspartate aminotransferase and alanine aminotransferase between individuals evidencing dual infection with hepatitis B and C viruses and healthy blood donors. However, in the group of patients with viral hepatitis of unknown etiology (non-A-E), those evidencing TTV viremia had statistically significant lower levels of alanine aminotransferase (P = .03) and aspartate aminotransferase (P = .04) than those who were TTV negative.

CONCLUSIONS

We can conclude that TTV is a frequent virus isolated from patients with various types of viral hepatitis, from cases of hepatitis without obvious viral agent, and from the healthy population. TTV has no effect on biochemical markers of associated viral hepatitis. It may be associated with a mild form of non-A-E hepatitis.

Performance of three PCR methods targeting different regions of viral genome for the detection of TTV in Non A-E hepatitis, chronic B and C hepatitis and healthy blood donors

TT virus (TTV) was suggested to be the etiologic agent for non A-E hepatitis but this could not yet be proven due to high detection rates not only in hepatitis but also in healthy persons and sensitivity differences of PCR methods employed. The aim of this study was to evaluate TTV DNA positivity in non A-E hepatitis cases, chronic HBV and HCV hepatitis cases and healthy blood donors via PCR systems that target all regions of the viral genome used for viral detection. 23 non A-E hepatitis, 28 chronic HCV, 21 chronic HBV cases and 56 healthy blood donors were included in the study and evaluated by PCR protocols that target 5′-UTR, 3′-UTR and N22 (ORF1) regions. As a result, 3′-UTR and 5′-UTR PCR had comparable detection rates that were higher than N22 PCR. Differences in detection rates among study groups were not statistically significant for any PCR method. Hepatic enzyme levels of the patients were not correlated with the presence of TTV DNA. Detection rate was significantly higher for Non A-E hepatitis group when positivity rates from all methods were combined. These results suggest an alteration of viral genotypes in Non A-E hepatitis which might be associated with pathogenesis.