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Published on: February 11, 2022
TT virus prevalence, viral loads and genotypic variability in saliva from healthy Japanese children
Masako Naganuma1, Norio Tominaga, Tsunetake Miyamura
1Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. macha.naganuma@nifty.ne.jp
Insights
TT virus (TTV) infection is common in children, with prevalence reaching 90% by 42 months. Saliva sampling effectively detected TTV DNA, showing higher loads in children than adults.
Area of Science:
- Virology
- Epidemiology
- Pediatrics
Background:
- TT virus (TTV) is a genetically diverse and widespread virus with unclear pathogenicity.
- Epidemiological data on TTV in children is limited due to challenges with blood sample collection from healthy infants.
Purpose of the Study:
- To investigate the epidemiology of TTV infection in early childhood using non-invasive saliva specimens.
- To compare TTV prevalence and genogroup distribution in children and adults.
Main Methods:
- Saliva samples were collected from children aged 1, 4, and 42 months.
- Paired saliva and peripheral blood mononuclear cells (PBMC) were collected from adults.
- TTV DNA was quantified using real-time PCR and genogroups (G1-G5) were identified via PCR.
Main Results:
- TTV DNA prevalence in children increased with age: 6% at 1 month, 34% at 4 months, and 90% at 42 months.
- TTV DNA was detected in 84% of adults; comparable levels were found in paired saliva and PBMC samples.
- Saliva TTV loads were significantly higher in children than adults; Genogroup 3 was most prevalent, followed by Genogroup 4 (infants) and Genogroup 1 (older children/adults).
Conclusions:
- TTV infection prevalence plateaus by 42 months of age in children.
- Saliva is a viable specimen for TTV detection and epidemiological studies in children.
- Distinct epidemiological patterns were observed across different TTV genogroups.
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.
