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. 2022 Nov 7;3(4):101872. doi: 10.1016/j.xpro.2022.101872

Figure 2.

Figure 2

Propagation and titration of SARS-CoV-2 virus in Vero-E6 Cells

(A) Representative bright field image of Vero-E6 Cell monolayer with apparent CPE 72 h after SARS-CoV-2 virus inoculation. Scale bar, 100 μm.

(B) Schematics of the virus serial dilutions preparation.

(C) Schematics of a 6-well plate used for the plaque assay after staining with the crystal violet solution (left) and the corresponding image of a real plaque assay plate (right) showing the formation of the plaques. Note that the well corresponding to the 10-7 virus dilution does not show plaque formation but presents a scratch (indicated with a yellow circle) that has been accidentally performed when removing the agarose layer with the flat spoon and can be confounded with a plaque.

(D) Representative fluorescent image of a typical 96-well plate prepared for virus titer assessment by the TCID50 assay (left). The table (right) shows a representative quantification of the number of positive infected wells that are used to calculate the virus titer by the Spearman-Karber method.