Liposome-mediated detection of SARS-CoV-2 RNA-positive extracellular vesicles in plasma

Plasma SARS-CoV-2 RNA may represent a viable diagnostic alternative to respiratory RNA levels that rapidly decline after infection. RT-qPCR reference assays exhibit poor performance with plasma, likely reflecting dilution and degradation of viral RNA released into the circulation, but these issues could be addressed by analyzing viral RNA packaged into extracellular vesicles (EVs). Herein we describe an assay approach where EVs directly captured from plasma are fused with reagent-loaded liposomes to sensitively amplify and detect a SARS-CoV-2 gene target. This approach accurately diagnosed COVID-19 patients, including challenging cases missed by RT-qPCR. SARS-CoV-2-positive EVs were detected at day one post-infection, and plateaued from day six to the day 28 endpoint in a non-human primate model, while 20–60 day signal durations were observed in young children. This nanotechnology approach, which uses a non-infectious sample, could thus improve COVID-19 diagnosis by extending virus detection windows to identify COVID-19 cases missed by current assays.