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TT virus infection during childhood
Hitoshi Ohto1, Niro Ujiie, Chikako Takeuchi
1Division of Blood Transfusion and Transplantation Immunology, Fukushima Medical University School of Medicine, Fukushima City, Japan. hit-ohto@fmu.ac.jp
Insights
TT virus (TTV) is commonly found in people, but how it spreads is unknown. This study suggests TTV is acquired by children through environmental interactions as they grow, not from their mothers.
Area of Science:
- Virology
- Infectious Diseases
- Hepatology
Background:
- TT virus (TTV) is prevalent globally, yet its transmission routes and persistence mechanisms remain unclear.
- Understanding TTV transmission is crucial for public health, especially concerning potential mother-to-infant spread.
Purpose of the Study:
- To investigate the mother-to-infant transmission of TT virus (TTV).
- To explore the acquisition routes and potential clinical significance of TTV in infants.
Main Methods:
- Longitudinal assessment of 54 infants born to 50 anti-HCV-positive mothers.
- Seminested PCR amplification of TTV DNA targeting the N22 variable coding region (genotypes 1-6).
- Comparison of nucleotide sequences between mothers and infants, including cord blood and infant blood samples at various ages.
Main Results:
- TTV DNA prevalence was 30% in mothers and 44% in infants.
- Infants born to TTV DNA-positive mothers showed a higher infection rate (87%) compared to those born to negative mothers (28%).
- TTV acquisition increased with age, suggesting non-parenteral, environment-dependent routes; maternal viral load was not a risk factor. Genotype 1 was cleared more rapidly by infants.
Conclusions:
- The primary route for TTV acquisition in children appears to be age-associated environmental interactions.
- Mother-to-infant transmission is not the main route, and TTV Genotype 1 may have a limited pathogenic role.
Background:
TT virus (TTV) is widespread in the general population, however, the mode of its transmission and the mechanism of maintaining it in the general population are unclear.
Study Design And Methods:
To determine the possible mother-to-infant route of transmission, 54 infants bom to 50 anti-HCV-positive mothers were assessed longitudinally. Nucleotide sequences amplified by seminested PCR with primers targeting the N22 variable coding region of genotypes 1 through 6 were compared in mothers and their infants.
Results:
The prevalence of TTV DNA was 30 percent (15/50; 95% CI, 18-45) in mothers and 44 percent (24/54; 95% CI, 31-59) in their infants. TTV DNA was detected during a follow-up period in 13 (87%; 95% CI, 60-98) of 15 infants born to infected mothers and in 11 (28%; 95% CI, 15-45) of 39 infants bom to DNA-negative mothers. None of 38 cord blood samples, but one of 14 blood samples, obtained at 1 month of age had detectable TTV DNA. The lowest infection rate at the earliest ages and the subsequent increasing prevalence of infection (22% at 6 months and 33% [43% cumulative rate] at 2 years) is consistent with an age-dependent acquisition of TTV by nonparenteral routes. In 13-mother-infant pairs positive for TTV DNA, six showed a high degree of nucleotide sequence similarity (99.1-100%), whereas the remaining seven pairs differed more than 10 percent from each other (46.8-89.2%). The viral load of matemal blood was not a plausible risk factor for transmission. Genotype 1, of which pathogenicity failed to be shown by measurement of hepatic enzymes, was more rapidly cleared (88 vs. 8% other genotypes, p < 0.001) among infants.
Conclusions:
These observations strongly suggest that the main factor for TTV acquisition in children involves their age-associated increase in environmental interactions with infectious materials. Genotype 1 might be involved in a weak or a limited pathologic role, which can possibly be diluted by other harmless genotypes.