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. 2020 Sep 29;12(10):1102. doi: 10.3390/v12101102

Figure 4.

Figure 4

Passage in the presence of trypsin generates trypsin independent M41-CK mutants. (A) Supernatant from the first passage of M41-CK in Vero cells in a low (0.2 µg/mL) or a high (2 µg/mL) concentration of TPCK-treated trypsin (P1-T) was used to infect Vero cells in the absence of trypsin (P2). The quantity of viral progeny in each sample of supernatant was assessed by titration in CK cells in triplicate. Average viral titres from the two infections were directly compared in order to identify populations of trypsin-independent mutants. The percentage of trypsin-independent viruses present in the P1-T sample was then calculated. (B) Supernatant from the fifth passage of M41-CK in Vero cells in a low (0.2 µg/mL) or a high (2 µg/mL) concentration of TPCK-treated trypsin (P5-T) was used to infect Vero cells in the absence of trypsin (P6). Average viral titres from the two infections were directly compared to identify populations of trypsin-independent mutants. The percentage of trypsin-independent viruses present in the P5-T sample was then calculated.