Department of Virology, University of Helsinki, 00290 Helsinki, Finland.
MediCity, University of Turku, 20520 Turku, Finland.
Viruses. 2022 Jun 11;14(6):1277. doi: 10.3390/v14061277.
Human torque teno viruses (TTVs) are a diverse group of small nonenveloped viruses with circular, single-stranded DNA genomes. These elusive anelloviruses are harbored in the blood stream of most humans and have thus been considered part of the normal flora. Whether the primary infection as a rule take(s) place before or after birth has been debated. The aim of our study was to determine the time of TTV primary infection and the viral load and strain variations during infancy and follow-up for up to 7 years. TTV DNAs were quantified in serial serum samples from 102 children by a pan-TTV quantitative PCR, and the amplicons from representative time points were cloned and sequenced to disclose the TTV strain diversity. We detected an unequivocal rise in TTV-DNA prevalence, from 39% at 4 months of age to 93% at 2 years; all children but one, 99%, became TTV-DNA positive before age 4 years. The TTV-DNA quantities ranged from 5 × 10 to 4 × 10 copies/mL, both within and between the children. In conclusion, TTV primary infections occur mainly after birth, and increase during the first two years with high intra- and interindividual variation in both DNA quantities and virus strains.
人类转矩腾病毒（TTVs）是一组多样化的小型无包膜病毒，具有圆形、单链 DNA 基因组。这些难以捉摸的环状病毒存在于大多数人类的血流中，因此被认为是正常菌群的一部分。原发性感染是在出生前还是出生后发生，一直存在争议。我们的研究目的是确定 TTV 原发性感染的时间以及婴儿期和随访期间长达 7 年的病毒载量和株变异。通过 pan-TTV 定量 PCR 对 102 名儿童的系列血清样本进行 TTV DNA 定量，并对代表时间点的扩增子进行克隆和测序，以揭示 TTV 株的多样性。我们检测到 TTV-DNA 流行率的明确上升，从 4 个月时的 39%上升到 2 岁时的 93%；除了一个孩子，所有孩子（99%）在 4 岁之前都转为 TTV-DNA 阳性。TTV-DNA 数量在儿童内部和之间均在 5×10 到 4×10 拷贝/ml 之间变化。总之，TTV 原发性感染主要发生在出生后，在头两年内增加，个体内和个体间的 DNA 数量和病毒株均存在高度的个体内和个体间变异。
