Adjuvants are essential for efficiently inducing an antigen-specific immune response in vaccine therapy. Single-stranded RNA (ssRNA) containing guanosine- and uridine-rich sequences is recognized by Toll-like receptor (TLR)7 and/or TLR8 and induces strong immune responses; thus, the application of ssRNA as an adjuvant is desirable. The development of a ssRNA-based adjuvant, however, requires the efficient delivery of ssRNA into the endosomes of antigen-presenting cells, where the TLRs exist. To achieve this, we developed a nanostructured RNA/DNA assembly using DNA nanotechnology, which can be efficiently recognized by antigen-presenting cells. The nanostructured RNA/DNA assembly, named tetrapodRD3, was designed using a 40-mer phosphorothioate-stabilized RNA and three 40-mer phosphodiester DNAs. TetrapodRD3 was more stable than ssRNA under serum conditions. The secreted alkaline phosphatase assay using HEK-Blue hTLR cells showed that tetrapodRD3 triggered human TLR8-specific responses. Fluorescently labeled tetrapodRD3 was efficiently taken up by murine dendritic DC2.4 cells and induced a high level of tumor necrosis factor-α release from the cells. Antigen presentation by the major histocompatibility complex class I on bone marrow-derived dendritic cells was significantly increased by the addition of an antigen along with tetrapodRD3. These results indicate that tetrapodRD3 constructed using DNA nanotechnology can be a useful adjuvant targeting human TLR8.

中文翻译：

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纳米结构RNA / DNA组装体作为靶向Toll样受体7/8的佐剂的发展。

佐剂对于在疫苗治疗中有效诱导抗原特异性免疫反应至关重要。含有鸟苷和尿苷富集序列的单链RNA（ssRNA）被Toll样受体（TLR）7和/或TLR8识别，并诱导强烈的免疫反应。因此，期望将ssRNA用作佐剂。但是，基于ssRNA的佐剂的开发需要将ssRNA有效地递送到存在TLR的抗原呈递细胞的内体中。为了实现这一目标，我们使用DNA纳米技术开发了一种纳米结构的RNA / DNA组件，可以被抗原呈递细胞有效识别。纳米结构的RNA / DNA组件，称为tetrapodRD3，是使用40硫代磷酸酯稳定的RNA和三个40硫磷酸二酯DNA设计的。在血清条件下，TetrapodRD3比ssRNA更稳定。使用HEK-Blue hTLR细胞进行的分泌式碱性磷酸酶测定显示，tetrapodRD3触发了人类TLR8特异性应答。荧光标记的tetrapodRD3被鼠树突状DC2.4细胞有效吸收，并诱导高水平的肿瘤坏死因子-α从细胞中释放。通过添加抗原以及tetrapodRD3，显着增加了主要的组织相容性复合体I类在骨髓来源的树突状细胞上的抗原呈递。这些结果表明，使用DNA纳米技术构建的tetrapodRD3可能是靶向人TLR8的有用佐剂。荧光标记的tetrapodRD3被鼠类树突状DC2.4细胞有效吸收，并诱导高水平的肿瘤坏死因子-α从细胞中释放。通过添加抗原以及tetrapodRD3，显着增加了主要的组织相容性复合体I类在骨髓来源的树突状细胞上的抗原呈递。这些结果表明，使用DNA纳米技术构建的tetrapodRD3可能是靶向人TLR8的有用佐剂。荧光标记的tetrapodRD3被鼠类树突状DC2.4细胞有效吸收，并诱导高水平的肿瘤坏死因子-α从细胞中释放。通过添加抗原以及tetrapodRD3，显着增加了主要的组织相容性复合体I类在骨髓来源的树突状细胞上的抗原呈递。这些结果表明，使用DNA纳米技术构建的tetrapodRD3可能是靶向人TLR8的有用佐剂。