Plasma SARS-CoV-2 RNA may represent a viable diagnostic alternative to respiratory RNA levels, which rapidly decline after infection. Quantitative PCR with reverse transcription (RT–qPCR) reference assays exhibit poor performance with plasma, probably reflecting the dilution and degradation of viral RNA released into the circulation, but these issues could be addressed by analysing viral RNA packaged into extracellular vesicles. Here we describe an assay approach in which extracellular vesicles directly captured from plasma are fused with reagent-loaded liposomes to sensitively amplify and detect a SARS-CoV-2 gene target. This approach accurately identified patients with COVID-19, including challenging cases missed by RT–qPCR. SARS-CoV-2-positive extracellular vesicles were detected at day 1 post-infection, and plateaued from day 6 to the day 28 endpoint in a non-human primate model, while signal durations for 20–60 days were observed in young children. This nanotechnology approach uses a non-infectious sample and extends virus detection windows, offering a tool to support COVID-19 diagnosis in patients without SARS-CoV-2 RNA detectable in the respiratory tract.

血浆 SARS-CoV-2 RNA 可能是呼吸道 RNA 水平的一种可行的诊断替代方法，后者在感染后迅速下降。带逆转录的定量 PCR (RT-qPCR) 参考测定在血浆中表现不佳，可能反映了释放到循环中的病毒 RNA 的稀释和降解，但这些问题可以通过分析包装到细胞外囊泡中的病毒 RNA 来解决。在这里，我们描述了一种测定方法，其中直接从血浆中捕获的细胞外囊泡与载有试剂的脂质体融合，以灵敏地扩增和检测 SARS-CoV-2 基因靶标。这种方法准确地识别了 COVID-19 患者，包括 RT-qPCR 遗漏的具有挑战性的病例。在感染后第 1 天检测到 SARS-CoV-2 阳性细胞外囊泡，并且在非人类灵长类动物模型中从第 6 天到第 28 天终点稳定，而在幼儿中观察到信号持续时间为 20-60 天。这种纳米技术方法使用非传染性样本并扩展了病毒检测窗口，提供了一种工具来支持对呼吸道中未检测到 SARS-CoV-2 RNA 的患者进行 COVID-19 诊断。