Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
Virus Res. 2010 May;149(2):211-6. doi: 10.1016/j.virusres.2010.01.019. Epub 2010 Feb 6.
APOBEC3 proteins function as part of innate antiviral immunity and induce G to A hypermutation in retroviruses and hepatitis B virus (HBV) genomes. Whether APOBEC3 proteins affect viruses that replicate without a reverse transcription step is unknown. TT virus (TTV), known to present in serum of healthy individuals and HBV carriers, has a single-stranded circular DNA genome and replicates without reverse transcription. In this study, we examined 67 blood samples obtained from healthy individuals and HBV carriers and observed G to A hypermutation of genomes of TTV in both healthy individuals and HBV carriers. During ALT flare-up in HBV carriers, G to A hypermutation of HBV increased, but TTV genomes significantly decreased in number and hypermutated TTV genomes became undetectable. Our results show that hypermutated TTV exist in healthy individuals and HBV carriers and that TTV genomes were susceptible to immune reaction directed to HBV by interacting with APOBEC3 proteins.
APOBEC3 蛋白作为先天抗病毒免疫的一部分，在逆转录病毒和乙型肝炎病毒 (HBV) 基因组中诱导 G 到 A 的超突变。APOBEC3 蛋白是否影响不需要逆转录步骤就能复制的病毒尚不清楚。已知 TT 病毒 (TTV) 存在于健康个体和 HBV 携带者的血清中，它具有单链环状 DNA 基因组，并且不需要逆转录就能复制。在这项研究中，我们检查了来自健康个体和 HBV 携带者的 67 份血液样本，并观察到在健康个体和 HBV 携带者中 TTV 基因组的 G 到 A 超突变。在 HBV 携带者的 ALT 爆发期间，HBV 的 G 到 A 超突变增加，但 TTV 基因组的数量显著减少，并且超突变的 TTV 基因组变得无法检测到。我们的结果表明，超突变的 TTV 存在于健康个体和 HBV 携带者中，并且 TTV 基因组易受针对 HBV 的免疫反应的影响，这是通过与 APOBEC3 蛋白相互作用而产生的。
