TT virus levels in the plasma of infected individuals with different hepatic and extrahepatic pathologies

Pistello, Mauro; Maggi, Fabrizio; Fornai, Claudia; Vatteroni, Maria Linda; Freer, Giulia; Morrica, Antonietta; Casula, F.; Marchi, Santino; Ricchiuti, A.; Ciccorossi, P.; Bendinelli, Mauro

doi:10.1016/s1590-8658(00)80718-5

Cited by 11 publications

(24 citation statements)

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“…Overall data are shown in Table 1. At baseline, TTV values ranged between 4.9 and 9.3 log 10 DNA copies per ml of plasma with a mean of 6.7 log 10 , confirming that plasma TTV loads may vary extensively in individual patients, but tend to be relatively high (31). At days 1 and 2 of therapy, two patients showed a marginal reduction of plasma TTV levels, but the others had either unchanged or slightly increased values relative to baseline.…”

Section: Resultsmentioning

confidence: 77%

“…TTV DNA quantification was carried out with a TaqMan real-time PCR targeted to a segment of the untranslated region (UTR) of the viral genome highly conserved among the ones deposited in gene banks at the time of writing: forward primer 5Ј-GTGCCGIAGGTGAGTTTA-3Ј, position 177 to 194; reverse primer 5Ј-AGCCCGGCCAGTCC-3Ј, position 226 to 239; probe 5Ј-TCAAGGGGCAATTCGGGCT-3Ј, position 205 to 223. The procedures used for copy number quantification and evaluation of intra-and interassay accuracy and reproducibility have been previously described (13,31). The lower limits of sensitivity were 1.0 ϫ 10 3 and 1.0 ϫ 10 2 TTV DNA copies per ml of plasma or per g of total PBMC DNA, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Although sensitive PCR assays have documented that TTV produces long-lasting, possibly permanent infections in most infected individuals and that plasma viremia is highly prevalent in the general population throughout the world (1,6,8,24,31), the natural history of TTV infection is still poorly understood. Suggestions that the liver is a major site of replication (26) have been questioned (9).…”

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confidence: 99%

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Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

Maggi¹,

Pistello²,

Vatteroni³

et al. 2001

J Virol

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TT virus (TTV) is a recently identified widespread DNA virus of humans that produces persistent viremia in the absence of overt clinical manifestations. In an attempt to shed light on the dynamics of chronic infection, we measured the levels of TTV in the plasma of 25 persistently infected patients during the first 3 months of alpha interferon (IFN-␣) treatment for concomitant hepatitis C virus (HCV) infection. The first significant decline of TTV loads was observed at day 3 versus day 1 for HCV. Subsequently, the loads of TTV became progressively lower in most patients, but some initial responders relapsed before the end of the follow-up, suggesting that at least in some subjects the effects of IFN on TTV can be very short-lived. No correlation between the responses of TTV and HCV to therapy was found. Fitting the viremia data obtained during the first week of treatment into previously developed mathematical models showed that TTV sustains very active chronic infections, with over 90% of the virions in plasma cleared and replenished daily and a minimum of approximately 3.8 ؋ 10 10 virions generated per day. Low levels of TTV were occasionally detected in the peripheral blood mononuclear cells of patients who had cleared plasma viremia, thus corroborating previous results showing that these cells may support TTV replication and/or persistence.

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Section: Resultsmentioning

confidence: 77%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

Maggi¹,

Pistello²,

Vatteroni³

et al. 2001

J Virol

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“…DNA was extracted from 200-l samples of all specimens by using the QIAamp DNA minikit (Qiagen, Chatsworth, Calif.) as specified by the manufacturer. The presence and load of TTV in nasal and plasma specimens were determined in a single step by a previously described TaqMan (TM)-PCR assay (14,27). This assay is based on a highly conserved segment of the viral untranslated region (Table 1) and has the potential for sensitive and specific detection of all the genotypes of TTV present in GenBank at the time of writing.…”

Section: Methodsmentioning

confidence: 99%

“…From the epidemiological standpoint, evidence has accumulated that TTV viremia is extremely common in the general population worldwide, starting from early childhood (1,5,10,26,27), implying the existence of a very efficient means of transmission, and the observation that infectious TTV is shed in the feces has led to the suggestion that the fecal-oral route is the most likely one (36). With regard to the life cycle in infected hosts, both selflimited and persistent systemic TTV infections have been described (reviewed in reference 5) and chronic TTV viremia has been shown to result from the production and clearance of 10 10 to 10 11 virions per day (16), indicative of the existence of body sites where the virus is continuously and actively replicated.…”

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confidence: 99%

TT Virus in the Nasal Secretions of Children with Acute Respiratory Diseases: Relations to Viremia and Disease Severity

Maggi¹,

Pifferi²,

Fornai³

et al. 2003

J Virol

196

215

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The natural history and pathogenic potential of the recently identified TT virus (TTV) are currently a matter of intensive investigation. In an attempt to shed some light on these issues, nasal and blood specimens of 1-to 24-month-old children hospitalized with a clinical diagnosis of acute respiratory disease (ARD) were examined for the presence, load, and genetic characteristics of TTV. The results have indicated that at least in young children, the respiratory tract not only represents a route by which abundant TTV can be shed into the environment but also may be a site of primary infection and continual replication. Although we found no compelling evidence that TTV was the direct cause of ARD in some of the children studied, the average loads of TTV were considerably higher in patients with bronchopneumonia (BP) than in those with milder ARD, raising interesting questions about the pathophysiological significance of TTV at this site. Furthermore, group 4 TTV was detected almost exclusively in children with BP.TT virus (TTV)-a small, nonenveloped virus with a singlestranded, negative-polarity, circular DNA genome of 3.8 kbwas initially thought to be a circovirus similar to chicken anemia virus, porcine circovirus, and other viruses of animals, but it is now under consideration as the possible type species of an independent virus family (17,18,34,35). The taxonomy of the vast array of related viral agents that have been identified in humans since the first description of TTV by Nishizawa et al. in 1997 (21) is also uncertain. Recently, however, Okamoto and Mayumi (22) have divided TTV isolates into at least four phylogenetic clusters differing by over 40% at the nucleotide level: group 1 has the original TTV isolate as the prototype and includes genotypes 1 to 6; group 2 has PMV as the prototype and comprises genotypes 7, 8, 17, 22, and 23; group 3 has SANBAN and SENV as representative isolates and includes genotypes 9 to 16 and 18 to 20; and group 4 has YONBAN as the prototype and includes genotype 21. Furthermore, while the present report was in preparation, the same group identified several novel genotypes within group 4 TTV as well as members of a proposed fifth group (26). Additional related viruses are more dissimilar due to their smaller genome (2.8 kb) and are presently designated TTV-like minivirus or TLMV (6,33,34).The natural history and pathogenic potential of TTV are currently the subject of active investigation. From the epidemiological standpoint, evidence has accumulated that TTV viremia is extremely common in the general population worldwide, starting from early childhood (1,5,10,26,27), implying the existence of a very efficient means of transmission, and the observation that infectious TTV is shed in the feces has led to the suggestion that the fecal-oral route is the most likely one (36). With regard to the life cycle in infected hosts, both selflimited and persistent systemic TTV infections have been described (reviewed in reference 5) and chronic TTV viremia has been shown to result fro...

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Relationship of TT virus and Helicobacter pylori infections in gastric tissues of patients with gastritis

Maggi

Marchi

Fornai

et al. 2003

Journal of Medical Virology

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Blood and gastric tissue biopsies of 34 patients with gastritis were tested for the presence of TT virus (TTV), a ubiquitous virus found in the blood of most humans. Thirty-one of these patients were TTV positive, and 27 patients had virus in both tissues. In addition, 13 of the patients who had TTV in gastric tissue were Helicobacter pylori positive. There was an association of higher TTV titers in gastric tissues of patients who were H. pylori positive than in those in whom the bacterium could not be detected. Furthermore, this association was stronger in H. pylori-positive patients with the presence of the cagA protein. Of 10 specimens in which genogroup determination was carried out in the gastric corpus, 5/5 that were H. pylori positive showed the presence of TTV genogroup 3, while for those that were H. pylori negative, 5/5 showed the presence of genogroup 1t. By contrast, genogroup 1 was found in the corpus of only one H. pylori-positive patient, and genogroup 3 in only one H. pylori-negative patient. The histological severity of gastritis did correlate significantly with loads in the gastric tissues. There was no significant difference in TTV titer in blood of patients regardless of H. pylori infection status. These findings pique interest in clarifying the role of TTV, alone or in association with H. pylori infection, in the pathogenesis of gastritis.

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TT virus levels in the plasma of infected individuals with different hepatic and extrahepatic pathologies

Cited by 11 publications

References 0 publications

Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

TT Virus in the Nasal Secretions of Children with Acute Respiratory Diseases: Relations to Viremia and Disease Severity

Relationship of TT virus and Helicobacter pylori infections in gastric tissues of patients with gastritis

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