Age-specific prevalence and transmission of TT virus

Abstract

TT virus (TTV) is an unenveloped, single-stranded DNA virus that was discovered recently in the sera of Japanese patients with posttransfusion hepatitis of unknown etiology. A high prevalence of TTV infection in blood donors of several countries, including Brazil, has been demonstrated. To study the variation in TTV prevalence between different age groups, sera from 223 individuals without liver disease, aged 0-80 years, were tested by the polymerase chain reaction for the presence of TTV DNA. All subjects were inhabitants of the city of Rio de Janeiro, Brazil. The prevalence increased continuously with age (P <.001), from 17% among children under the age of 11 years, to 57% in people older than 50 years. To assess vertical transmission, sera from 105 unselected, consecutive parturient women attending a public maternity hospital were paired with cord bloods and examined for the presence of TTV DNA. Thirty-seven (35%) mothers were found to be TTV infected. Seven cord bloods were also positive, suggesting the possible transplacental transmission of the virus. Furthermore, a direct correlation between TTV viremia and presence of antibodies to the enterically transmissible hepatitis A virus (HAV) was observed in this group of women, with a relative risk of TTV infection of 5.09 (95% confidence interval 0.76-34.03) for women with anti-HAV, compared with women without. This finding suggested that the fecal-oral route might be an important route of TTV transmission.

TT virus infection in children and adults who visited a general hospital in the south of Brazil for routine procedure

“…This group was quite representative of the population of the south of Brazil. Taken together with previous studies showing high prevalences (24-65%) of TTV infection in blood donors , parturient women (Saback et al 1999), and health care workers (Niel et al 2000) from Rio de Janeiro, as well as hepatitis patients from São Paulo and Pará states (Pinho et al 1998), the results presented here constitute additional evidence that a large part of the Brazilian population is chronically infected with TTV.…”

“…This corroborated observations made in Japan that showed a high prevalence in a preschool group, followed by a decline during the adolescence and a new elevation among young adults (Yamada-Osaki et al 1998). However, a similar curve of age-specific TTV seroprevalence was not observed among healthy individuals living in the city of Rio de Janeiro, where the prevalence, measured using the Tanaka´s PCR detection system, increased continuously with age (Saback et al 1999). The reasons which could explain this discrepancy are still not clear.…”

Virus target cell conditioning model to explain some epidemiologic characteristics of childhood leukemias and lymphomas

“…Transplacental or perinatal infection results in virus persistence, as observed in previous studies for established TT virus genotypes. [58][59][60] The expansion of susceptible cells in the course of a newborn child's development, as well as acquisition of new infections with additional TTV types during the first year of life, 49 should result in an increasing number of persistently infected cells and correspondingly to a steadily increasing viral load. It has recently been reported that TT virus concentrations increase with age.…”

“…It has recently been reported that TT virus concentrations increase with age. 58 Partial homology of this viral DNA with host cell genes frequently engaged in translocations of leukemic or lymphoma cells should increase the risk for specific translocations in the course of viral and cellular DNA replication proportional to the number of viral DNA-positive cells. Occasionally, such translocations are also found in healthy individuals, as for example described for the lymphoma-associated translocation t(14;18).…”

Isolation of Multiple TT Virus Genotypes from Spleen Biopsy Tissue from a Hodgkin's Disease Patient: Genome Reorganization and Diversity in the Hypervariable Region

“…Viral particles have been purified from feces (17, 34) and, in addition, are excreted in saliva, breast milk, and bile juice (9,38,47,49). Transplacental transmission from mother to child has been controversial, but postnatal transmission has been confirmed repeatedly (15,20,24,30,33,37,48,51,52,57 (39,44). Peripheral blood mononuclear cells act as a reservoir for TTV (41), but the highest viral load is found in the granulocytes (54).…”