Fig. 1.

Virucidal activity of extraction buffers in rapid SARS-CoV-2 antigen tests. a, b) A solution of 10% SARS-CoV-2 D614G, 10% interfering substance (5% (w/v) albumin fraction V, 0.4% (w/v) mucin from bovine submaxillary glands type I-S, 5% (w/v) yeast extract) and 80% of the respective buffer B1-B10 or phosphate buffer saline (PBS) was analyzed according to quantitative suspension tests as described in DIN EN 14,476 [8,9]. After incubation for (a) 1 min or (b) 15 min, viral infectivity was quantified by TCID₅₀ endpoint titration on Vero E6 cells. Detection limits caused by cytotoxicity of buffers are shown in gray, infectious titers in black. c) 10% virus (D614G variant or VOCs B.1.1.7 or B.1.351) was spiked into 90% pooled saliva and mixed 1:4 with B10 or PBS. After the indicated incubation times, an endpoint titration on Vero E6 cells was performed to determine TCID₅₀/ml. Dotted lines indicate limit of detection due to cytotoxicity. a–c) Shown are means of three independent experiments ± SD.