TTV infection in children born to mothers infected with TTV but not with HBV, HCV, or HIV

Natural recombination of the torque teno canis virus within the ORF1, -2, and -3 genes and the untranslated region

The torque teno canis virus (TTCaV) was first reported in 2001 and it shares similarities with the known Torque teno virus (TTV) in terms of genomic organization and putative transcriptional features. It is a single-stranded DNA virus characterized by high rates of recombination and nucleotide substitution, like RNA viruses. Studies reported recombination events in torque teno virus; however, there is limited reporting of TTCaV reorganization events. This study screened fecal samples from domestic dogs in Henan Province. There was a positivity rate of 16.5% (19/115) for TTCaV. Four nearly complete TTCaV genomes, namely Canine/HeNan/4, 5, 6, and 13/2019, were obtained from the 19 positive fecal samples, whose genome sequence was obtained using gap-filling PCR. Sequence analysis revealed two unique amino acid mutation sites in the TTCaV strains, K278Q (compared with the first isolate Cf-TTV10 in Japan) and V/L268I (compared with the TTCaV strain from southern China). Subsequently, 17 near full-length TTCaV genome sequences were subjected to phylogenetic and recombination detection program analyzes. We obtained evidence supporting recombination events in the Chinese TTCaV strains. These findings suggest that mutation and recombination occurred in the three individual gene segments (ORF1, ORF2, ORF3) and the untranslated region, an area of major recombination in the Chinese TTCaV strain GX265 genome. Interestingly, the TTCaV strain (Canine/HeNan/6/2019) was a major parent involved in the genetic recombination of the GX265 strain. This study provides insights into the genetic variability and evolution of TTCaV.

Genomic Diversity of Torque Teno Virus in Blood Samples from Febrile Paediatric Outpatients in Tanzania: A Descriptive Cohort Study

Torque teno virus (TTV) is considered to be an ubiquitous member of the commensal human blood virome commonly reported in mixed genotype co-infections. This study investigates the genomic diversity of TTV in blood samples from 816 febrile Tanzanian children. Metagenomic next-generation sequencing was used to screen for TTV in individual blood samples from a cohort of 816 febrile Tanzanian paediatric outpatients. For positive samples, the number of TTV species and genotypes present were evaluated. We investigate the linear relationship between individual TTV diversity and the patient age by linear regression. TTV was detected in 97.2% of sera. ORF1 analysis revealed the presence of 149 genotypes from 38 species, suggesting the presence of 13 new species. These genotypes were mostly present as co-infections with a median of 11 genotypes/subject (range: 1−71). In terms of species, we found a median of nine species/subject (range: 1−29). We further show a significant association between the diversity of co-detected TTV and the age of the subjects (p value < 0.0001). This study shows that significant TTV genomic diversity is acquired by the age of five and that this diversity tends to increase with age, which indicates a repetitive TTV acquisition during the first months/years of life.

Early-Life Colonization by Anelloviruses in Infants

Anelloviruses (AVs) are found in the vast majority of the human population and are most probably part of a healthy virome. These viruses infect humans in the early stage of life, however, the characteristics of the first colonizing AVs are still unknown. We screened a collection of 107 blood samples from children between 0.4 and 64.8 months of age for the presence of three AV genera: the Alpha-, Beta- and Gammatorquevirus. The youngest child that was positive for AV was 1.2 months old, and a peak in prevalence (100% of samples positive) was reached between the twelfth and eighteenth months of life. Intriguingly, the beta- and gammatorqueviruses were detected most at the early stage of life (up to 12 months), whereas alphatorqueviruses, the most common AVs in adults, increased in prevalence in children older than 12 months. To determine whether that order of colonization may be related to oral transmission and unequal presence of AV genera in breast milk, we examined 63 breast milk samples. Thirty-two percent of the breast milk samples were positive in a qPCR detecting beta- and gammatorqueviruses, while alphatorqueviruses were detected in 10% of the samples, and this difference was significant (p = 0.00654). In conclusion, we show that beta- and gammatorqueviruses colonize humans in the first months of life and that breastfeeding could play a role in AV transmission.

Survey of Viral Reactivations in Elite Athletes: A Case-Control Study

Exercise-induced immune perturbations have been proposed to increase susceptibility to viral infections. We investigated the replication of persisting viruses as indicators of immune function in elite cross-country skiers after ten months of sustained high-performance exercise. The viruses evaluated, nine human herpesviruses (HHVs) and torque teno virus (TTV), are typically restrained in health but replicate actively in immunosuppressed individuals. We collected sera from 27 Finnish elite cross-country skiers at the end of the competition's season and 27 matched controls who perform moderate exercise. We quantified all the HHVs and-TTV via highly sensitive qPCRs. To verify equal past exposures between the groups, we assessed the IgG antibody prevalences toward HHV-4 (Epstein-Barr virus, EBV) and HHV-5 (human cytomegalovirus, HCMV). We found equal TTV DNA prevalences in athletes (63%) and controls (63%) and loads with respective geometric means of 1.7 × 103 and 1.2 × 103 copies/mL of serum. Overall, the copy numbers were low and consistent with those of healthy individuals. Neither of the groups presented with herpesvirus viremia despite similar past exposures to HHVs (seroprevalences of EBV 70% vs. 78% and HCMV 52% vs. 44% in athletes and controls, respectively). We found no evidence of increased replication of persistent viruses in elite athletes, arguing against impaired viral immunity due to high-performance exercise.

Unmapped exome reads implicate a role for Anelloviridae in childhood HIV-1 long-term non-progression

Human immunodeficiency virus (HIV) infection remains a significant public health burden globally. The role of viral co-infection in the rate of progression of HIV infection has been suggested but not empirically tested, particularly among children. We extracted and classified 42 viral species from whole-exome sequencing (WES) data of 813 HIV-infected children in Botswana and Uganda categorised as either long-term non-progressors (LTNPs) or rapid progressors (RPs). The Ugandan participants had a higher viral community diversity index compared to Batswana (p = 4.6 × 10-13), and viral sequences were more frequently detected among LTNPs than RPs (24% vs 16%; p = 0.008; OR, 1.9; 95% CI, 1.6-2.3), with Anelloviridae showing strong association with LTNP status (p = 3 × 10-4; q = 0.004, OR, 3.99; 95% CI, 1.74-10.25). This trend was still evident when stratified by country, sex, and sequencing platform, and after a logistic regression analysis adjusting for age, sex, country, and the sequencing platform (p = 0.02; q = 0.03; OR, 7.3; 95% CI, 1.6-40.5). Torque teno virus (TTV), which made up 95% of the Anelloviridae reads, has been associated with reduced immune activation. We identify an association between viral co-infection and prolonged AIDs-free survival status that may have utility as a biomarker of LTNP and could provide mechanistic insights to HIV progression in children, demonstrating the added value of interrogating off-target WES reads in cohort studies.

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.

Higher frequency of vertebrate-infecting viruses in the gut of infants born to mothers with type 1 diabetes

BACKGROUND

Microbial exposures in utero and early life shape the infant microbiome, which can profoundly impact on health. Compared to the bacterial microbiome, very little is known about the virome. We set out to characterize longitudinal changes in the gut virome of healthy infants born to mothers with or without type 1 diabetes using comprehensive virome capture sequencing.

METHODS

Healthy infants were selected from Environmental Determinants of Islet Autoimmunity (ENDIA), a prospective cohort of Australian children with a first-degree relative with type 1 diabetes, followed from pregnancy. Fecal specimens were collected three-monthly in the first year of life.

RESULTS

Among 25 infants (44% born to mothers with type 1 diabetes) at least one virus was detected in 65% (65/100) of samples and 96% (24/25) of infants during the first year of life. In total, 26 genera of viruses were identified and >150 viruses were differentially abundant between the gut of infants with a mother with type 1 diabetes vs without. Positivity for any virus was associated with maternal type 1 diabetes and older infant age. Enterovirus was associated with older infant age and maternal smoking.

CONCLUSIONS

We demonstrate a distinct gut virome profile in infants of mothers with type 1 diabetes, which may influence health outcomes later in life. Higher prevalence and greater number of viruses observed compared to previous studies suggests significant underrepresentation in existing virome datasets, arising most likely from less sensitive techniques used in data acquisition.

Assessment of prevalence and load of torquetenovirus viraemia in a large cohort of healthy blood donors

OBJECTIVES

Torquetenovirus (TTV) is an emerging marker of functional immune competence with the potential to predict transplant-related adverse events. A large-scale epidemiological study was performed to understand how basal values vary in healthy individuals according to age and gender.

METHODS

We tested plasma from 1017 healthy blood donors aged 18-69 years. The presence and load of TTV were determined by a real-time PCR assay. A sub-cohort of 384 donors was tested for anti-cytomegalovirus IgG antibodies, and 100 participants were also tested for TTV viraemia on a paired whole blood sample.

RESULTS

The overall prevalence of TTV was 65% (657/1017) with a mean (±SD) growth of 5 ± 4% every 10 years of age increase, but stably higher in males (465/690, 67%) than in females (192/327, 59%). Mean (±SD) TTV load was 2.3 ± 0.7 Log copies/mL with no sex difference. TTV viraemia showed modest increases along 10-year age intervals (mean ± SD: 0.3 ± 0.1). TTV viraemia in donors sampled 2 years later remained stable (mean ± SD: 2.3 ± 0.8 versus 2.2 ± 0.7 Log copies between samples). Twenty-six per cent (9/34) of blood donors with TTV-negative plasma scored positive when whole blood was tested, and the donors with positive plasma showed a mean (±SD) 1.4 ± 0.5 Log increase in copy numbers when whole blood was tested.

CONCLUSIONS

This study establishes the mean value of TTV viraemia in plasma in healthy blood donors and suggests that ageing causes only minimal increases in TTV viraemia.

Detection and phylogenetic analysis of torque teno virus (TTV) carried by murine rodents and house shrews in China

Between May 2015 and May 2017, 496 animals (473 murine rodents and 23 house shrews) were captured in six regions of China. A total of 22.8% (113/496) of throat swabs, 29.1% (142/488) of fecal samples and 23.8% (54/227) of serum samples tested positive for rodent torque teno virus 3 (RoTTV3). The positive rate in Rattus norvegicus was higher than the rate in Rattus tanezumi and Rattus losea. Of 23 house shrews, one throat swab and one serum sample were positive for RoTTV3. Ten murine rodents were simultaneously positive for RoTTV3 in throat swab, fecal and serum samples. Phylogenetic analysis showed that the 12 near-full length genomes of RoTTVs sequences obtained in this study represented a novel RoTTV genotype (RoTTV3). In conclusion, high prevalence rates of RoTTV3 were found in three common murine rodents in China, and the RoTTV3 obtained in this study were classified as a novel genotype of RoTTV.

Torque teno virus dynamics during the first year of life

Background

Torque teno virus is a small chronically persisting circular negative ssDNA virus reaching near 100% prevalence. It is reported to be a marker for immune function in immunocompromised patients. The possibility of vertical maternal-fetal transmission remains controversial but incidence rate of TTV DNA in children increased with age. TTV dynamics well studied for allogeneic hematopoietic stem cell transplantation as a predictor of post-transplant complications but there is no viral proliferation kinetics data for other patient groups or healthy individuals. The aim of this study was to determine TTV dynamics during the first year of life of healthy infants.

Methods

Ninety eight clinically healthy breastfeeding infants (1–12 months of age) were analyzed by quantitative PCR for the whole blood TTV load with the test sensitivity of about 1000 viral copies per milliliter of blood (total number of samples including repeatedly tested infants was 109).

Results

67% of all analyzed samples were TTV-positive demonstrating significant positive correlation between age and TTV load (r = 0.81, p < 0.01).

Conclusions

This is the first study to suggest that viral load increases during the first year of life reaching a plateau after 6 months with strong proliferation for the first 60 days. Our data well correlates with TTV dynamics in patients following allogeneic hematopoietic stem cell transplantation.

Transplacental transmission of torque teno virus

Background

TTV has been detected in almost every human tissue type or body fluid reaching near 100% prevalence. Several studies report mother-to-child postnatal transmission of TTV in infancy but the risk of transplacental transmission of TTV is still unclear.

Methods

The blood and plasma collected postpartum from 100 mother-child pairs were analyzed using TTV-specific qPCR. Samples were collected from the peripheral vein of the mother and the umbilical cord.

Results

Eighty four percent of pregnant women were TTV positive (median titers: 8 × 10⁴ copies/mL; range: 10³ – 3 × 10⁷). The TTV load in plasma was approximately 100 times lower than in whole blood. TTV was not detected in any of cord blood samples.

Conclusions

Our data demonstrate the lack of transplacental transmission of TTV (or effective prenatal inhibition of viral proliferation). The presence of the virus in infants may be associated with mother-to-child transmission through breast feeding or other routes of transmission.

Local Virus Extinctions following a Host Population Bottleneck

A small number of African green monkeys (AGMs) were introduced into the Caribbean from West Africa in the 1600s. To determine the impact of this population bottleneck on the AGM virome, we used metagenomics to compare the viral nucleic acids in the plasma of 43 wild AGMs from West Africa (Gambia) to those in 44 AGMs from the Caribbean (St. Kitts and Nevis). Three viruses were detected in the blood of Gambian primates: simian immunodeficiency virus (SIVagm; in 42% of animals), a novel simian pegivirus (SPgVagm; in 7% of animals), and numerous novel simian anelloviruses (in 100% of animals). Only anelloviruses were detected in the Caribbean AGMs with a prevalence and levels of viral genetic diversity similar to those in the Gambian animals. A host population bottleneck therefore resulted in the exclusion of adult-acquired SIV and pegivirus from the Caribbean AGMs. The successful importation of AGM anelloviruses into the Caribbean may be the result of their early transmission to infants, very high prevalence in African AGMs, and frequent coinfections with as many as 11 distinct variants.

IMPORTANCE

The extent to which viruses can persist in small isolated populations depends on multiple host, viral, and environmental factors. The absence of prior infections may put an immunologically naive population at risk for disease outbreaks. Isolated populations originating from a small number of founder individuals are therefore considered at increased risk following contact with populations with a greater variety of viruses. Here, we compared the plasma virome of West African green monkeys to that in their descendants after importation of a small number of animals to the Caribbean. A lentivirus and a pegivirus were found in the West African population but not in the Caribbean population. Highly diverse anelloviruses were found in both populations. A small founder population, limited to infants and young juvenile monkeys, may have eliminated the sexually transmitted viruses from the Caribbean AGMs, while anelloviruses, acquired at an earlier age, persisted through the host population bottleneck.

Detection and genotyping of torque teno virus (TTV) in healthy blood donors and patients infected with HBV or HCV in Qatar

Torque Teno virus (TTV) has been associated with non A-G hepatitis. The goal of this study was to estimate the infection rates and genotypic characteristics of TTV in the State of Qatar. A total of 644 blood samples representing different nationalities: (i) Qatari (118) and (ii) non-Qatari (526) nationals (mostly from Arab and South Eeast Asia countries) were tested for the presence of TTV DNA by nested PCR. The majority (573) of the blood samples belonged to healthy blood donors, whereas 54 and 53 of the blood samples belonged to patients infected with hepatitis B virus (HBV) and hepatitis C virus (HCV), respectively. The results obtained showed that the TTV infection rates in the healthy blood donors, and those infected with HBV or HCV patients were 81.4, 90.75 and 84.9%, respectively. Significant association between TTV viremia and age, or nationality was observed. Sequence analysis of PCR fragments amplified from the 5'-untranslated region (5'-UTR) of all (531) TTV positive samples showed that 65.5% (348/531) of the PCR fragment sequences were classified into main genogroup 3, followed by main genogroups 5 (24%), 2 (5.8%), and 1 (4.7%). Genogroup 4 was not detected among the our studied subjects. Phylogenetic and pairwise analyses using sequences from TTV viremic samples also showed an overall close similarity to the main genogroup 3. In conclusion, there was no significant difference in the rates of TTV detection among Qataris and non-Qataris and several genotypes, mainly genotype 3, were isolated.

Molecular investigation of Torque teno sus virus in geographically distinct porcine breeding herds of Sichuan, China

Background

Torque teno sus virus (TTSuV), infecting domestic swine and wild boar, is a non-enveloped virus with a circular, single-stranded DNA genome. which has been classified into the genera Iotatorquevirus (TTSuV1) and Kappatorquevirus (TTSuV2) of the family Anelloviridae. A molecular study was conducted to detect evidence of a phylogenic relationship between these two porcine TTSuV genogroups from the sera of 244 infected pigs located in 21 subordinate prefectures and/or cities of Sichuan.

Results

Both genogroups of TTSuV were detected in pig sera collected from all 21 regions examined. Of the 244 samples, virus from either genogroup was detected in 203 (83.2%), while 44 animals (18.0%) were co-infected with viruses of both genogroups. Moreover, TTSuV2 (186/244, 76.2%) was more prevalent than TTSuV1 (61/244, 25%). There was statistically significant difference between the prevalence of genogroups 1 infection alone (9.4%, 23/244) and 2 alone (64.8%, 158/244), and between the prevalence of genogroups 2 (76.2%, 186/244) and both genogroups co-infection (18.0%, 44/244). The untranslated region of the swine TTSuV genome was found to be an adequate molecular marker of the virus for detection and surveillance. Phylogenetic analysis indicated that both genogroups 1 and 2 could be further divided into two subtypes, subtype a and b. TTSuV1 subtype b and the two TTSuV2 subtypes are more prevalent in Sichuan Province.

Conclusions

Our study presents detailed geographical evidence of TTSuV infection in China.

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.

Nearly constant shedding of diverse enteric viruses by two healthy infants

Stool samples from two healthy infant siblings collected at about weekly intervals during their first year of life were analyzed by PCR for 15 different enteric viral genera. Adenovirus, Aichi virus, Anellovirus, Astrovirus, Bocavirus, Enterovirus, Parechovirus, Picobirnavirus, and Rotavirus were detected. Not detected were Coronavirus, Cardiovirus, Cosavirus, Salivirus, Sapovirus, and Norovirus. Long-term virus shedding, lasting from one to 12 months, was observed for adenoviruses, anelloviruses, bocaviruses, enteroviruses, parechoviruses, and picobirnaviruses. Repeated administration of oral poliovirus vaccine resulted in progressively shorter periods of poliovirus detection. Four nonpolio enterovirus genotypes were also detected. An average of 1.8 distinct human viruses were found per time point. Ninety-two percent (66/72) of the fecal samples tested contained one to five different human viruses. Two British siblings in the mid-1980s showed nearly constant fecal viral shedding. Our results demonstrate that frequent enteric infections with diverse viruses occur during early childhood in the absence of severe clinical symptoms.

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.

Swine torque teno virus (TTV) infection and excretion dynamics in conventional pig farms

Torque teno virus (TTV) is a non-enveloped, single-stranded DNA (ssDNA) virus infecting human and non-primate species. Two genogroups of TTV (TTV1 and TTV2) have been described in swine so far. In the present study, TTV1 and TTV2 prevalences in serum, and nasal as well as rectal swabs of 55 randomly selected piglets from seven Spanish multi-site farms, were monitored from 1 to 15 weeks of age. Also, blood from their dams (n=41) were taken at 1 week post-farrowing. Samples were tested by means of two TTV genogroup specific PCRs. Although prevalence of TTV1 and TTV2 in sows was relatively high (54% and 32%, respectively), it was not directly associated to their prevalence in the offspring. Percentage of viremic pigs for both TTV genogroups followed similar dynamics, increasing progressively over time, with the highest rate of detection at 11 weeks of age for TTV1 and at 15 weeks for TTV2. Forty-two (76%) and 33 (60%) of the 55 studied pigs were TTV1 and TTV2 PCR positive in serum, respectively, in more than one sampling time. TTV1 and TTV2 viremia lasted in a number of animals up to 15 and 8 weeks, respectively. Co-infection with both TTV genogroups in serum was detected at all sampling points, but at 1 week of age. On the contrary, there were animals PCR negative to both genogroups in serum at all sampling times but at 15 weeks of age. During the study period, TTV1 and TTV2 nasal shedding increased also over time and faecal excretion was intermittent and of low percentage (<20%). In conclusion, the present study describes for the first time the infection dynamics of TTV1 and TTV2 as well as the nasal and faecal excretion throughout the life of pigs from conventional, multi-site farms. Moreover, results indicate that both swine TTV genogroups are able to establish persistent infections in a number of pigs.

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.

Evidence of Torque teno virus (TTV) vertical transmission in swine

Routes of swine torque teno virus (TTV) transmission have been minimally investigated in the pig population. Current knowledge suggests the faecal-oral route as the most probable way of viral dissemination. Other transmission routes, such as mother-to-infant, have been studied in humans, but no information is available for swine. Thus, the objective of the present study was to determine the prevalence of two swine TTV genogroups, TTV1 and TTV2, in colostrum samples (n=61) and sera samples from sows (n=10) and stillborn pigs coming from them (n=30). Colostrum was fractioned into two components, milk whey and cell pellets, and 26 out of 61 milk whey samples and 30 out of 58 cell pellets analyzed contained TTV1 or TTV2 genomes, respectively, detected by specific PCR methods. Six and 3 out of 10 serum samples from sows were positive for TTV1 and TTV2 DNA, respectively. Finally, 15 out of 30 sera from stillborns were PCR positive for TTV1, but only 2 were TTV2 positive. Positive stillborns were always infected with the same TTV genogroup as their mothers. However, TTV sequence analysis determined that sequences obtained from sows and their stillborns were not identical. In conclusion, our results indicated that swine TTVs can be transmitted vertically, and suggest that different sow-to-piglet transmission routes may coexist, including transplacental/intra-uterine as well as through lactation. This study represents the first description of swine TTV presence in colostrum and stillborn piglets.

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.

Detection of swine Torque teno virus genogroups 1 and 2 in boar sera and semen

Torque teno virus (TTV) is a non-enveloped, circular, single-stranded DNA virus infecting swine and several other species. TTV is nowadays considered a non-pathogenic virus in all species where it has been found. In the present study, the prevalence of two distinct swine TTV genogroups in boar semen and sera was determined by a nested PCR method. Furthermore, association between TTV infection and semen qualitative and quantitative parameters was analyzed. TTV was detected in 74% of boar sera and 72% in semen. The prevalence of genogroup 1 in sera and semen were 64% and 55%, respectively, while lower prevalence of genogroup 2 was observed in both sera (38%) and semen (32%). Some significant associations of TTV infection on semen characteristics in boar genetic lines were observed, but qualitative and quantitative semen parameters obtained in studied boars fall into normal expected ranges. Therefore, TTV semen infection was not evidenced to be harmful for the studied qualitative and quantitative parameters of semen. The high rate of TTV in semen suggests that sexual route might contribute to the transmission of the virus. It is presently unknown if this potential vertical transmission of swine TTV implies any effect on female reproductive tract. This study also represents the first description of swine TTV presence in semen.

Torque teno virus (TTV) is highly prevalent in the European wild boar (Sus scrofa)

The present study represents the first survey of Torque teno virus (TTV) prevalence in European wild boar (Sus scrofa). The prevalence of two distinct TTV genogroups in 178 Spanish wild boar sera from different geographic regions, management conditions, gender and age was determined by a nested PCR method. The overall prevalence of TTV genogroups was 84% (58% for genogroup 1 and 66% for genogroup 2), and differences between genogroup prevalence were observed depending on the geographical region analysed. Significantly higher prevalence for TTV genogroup 2 was found in fenced managed wild boar, juvenile animals and females. No other significant differences in TTV genogroup prevalence were observed. The phylogenetic analysis of nucleotide sequences obtained from the untranslated region of selected samples revealed that the same TTV genogroups are infecting wild boar and domestic pig. The results indicate that TTV is apparently ubiquitous in European wild boar populations.