Fig. 2.

Interferon sensitivity of the different rescued viruses. The different rescued viruses, as in Fig. 1, were titrated using a TCID₅₀ assay in the absence or presence of 200 IU/ml of murine β-interferon, as described in Section Material and methods. Average fold-reduction in virus titers for independent experiments for each sample is presented on a logarithmic scale with error bars indicating the maximal value observed for each virus (n=5 for the parental viruses, n=3 for the two viruses harboring substitution of the L2 gene and n=2 for the other viruses). In both the T3D^S and P4L-12 background, only L2 gene substitution statistically altered interferon sensitivity, at p=0.002 and p=0.05 respectively using unpaired Student׳s t-test.