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. 2022 May 9;11:e69949. doi: 10.7554/eLife.69949

Figure 4. COV-ID on saliva collected on paper.

Figure 4.

(A) Scheme for COV-ID on viral RNA absorbed on paper. (B) PCR reactions from paper samples immersed in water with indicated viral concentrations then amplified with N2 COV-ID primers. (C) Scheme for COV-ID on saliva spiked with viral and RNA and absorbed on paper. (D) Same as (B) but on saliva absorbed on paper. (E) SARS-CoV-2 virus was added to saliva and prepared as in (C).Reverse transcription loop-mediated isothermal amplification (RT-LAMP) and sequencing was carried out in presence of calibration standard RNA. Viral reads are presented as ratio against the sum of STATH and N2 synthetic calibration standard (SCS) reads. Positive threshold was set as 2x maximum value in negative saliva and indicated by dashed horizontal line. (F–G) Paper-based COV-ID workflow (F) and cost calculations (G). Saliva is collected orally on a precut strip of paper, from which a 2 mm square would be cut out and added to a reaction vessel containing TCEP/EDTA inactivation buffer and processed as shown in (C).

Figure 4—source data 1. Uncropped blot for Figure 4B.
Figure 4—source data 2. Uncropped blot for Figure 4D.