Suchergebnisse

The current gold standard technique for SARS-CoV-2 diagnostics is hydrolysis probe-based RT-qPCR. Reliable testing requires reliable control reagents to monitor the efficiency of RNA extraction, reverse transcription and PCR amplification. Here we describe a custom RNA packaging system from the plant virus cowpea mosaic virus to produce virus-like particles that encapsidate specifically designed portions of the genome of SARS-CoV-2, the causative agent of COVID-19. These encapsidated mimics are highly stable particles which can be used either to spike patient swab samples for use as an in-tube extraction and reaction positive control in multiplex RT-qPCR, or alone as a side-by-side mock-positive control reagent. The selection of sequences in the packaged pseudogenomes ensures that these mimics are compatible with the most commonly used primer/probe combinations for SARS-CoV-2 diagnostics (including German Berlin Charité Hospital, American CDC, and Chinese CDC protocols). The plant transient expression system used to produce these encapsidated mimics is inherently low-cost, and sufficiently high-yielding that a single laboratory-scale preparation can provide enough positive control reagent for millions of tests. ; We thank Horticultural Services at the John Innes Centre (JIC) for providing the plants necessary for this work while under the COVID-19 restrictions. At JIC this work was supported by the United Kingdom Biotechnology and Biological Sciences Research Council (BBSRC) Institute Strategic Programme Grant "Molecules from Nature – Enhanced Research Capacity" (BBS/E/J/000PR9794), and the John Innes Foundation. This work was further supported by the European Union's Horizon 2020 programme under Grant Agreements 760331 (Newcotiana) and 774078 (Pharma-Factory). Julian Ma also acknowledges generous support from the Sir Joseph Hotung Charitable Trust.