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determination, samples were precipitated with 10% trichloroacetic acid on ice and washed twice with 5% trichloroacetic acid. Acid-precipitable radioactivity was measured by scintillation counting.

Interferon induction

IFN-P ąuantification was performed by enzyme-linked immunosorbent assay (ELISA) according to the manufactureris instructions (Mouse IFN-Beta ELISA, PBL Biomedical Laboratories, New Brunswick, NJ) on supematants from L929 cells infected with an MOI of 0.1 or 20 collected at 6, 12, 24 or 36h post-infection as described above.

Oncoiysis

Mouse Lewis Lung 3LL carcinoma, mouse B16 melanoma, mouse EL4 lymphoma, human Jurkat T celi lymphoma, human HepG2 hepatocarcinoma, mouse MC57 fibrosarcoma, and mouse L929 fibroblasts were infected at an MOI of 20 or mock-infected as described above. Celi viability was measured by mitochondrial activity determination at 6, 12, 24, 36, 48 and 60h post-infection using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay (Celi Proliferation Kit I MTT, Roche Diagnostics, Mississauga, ON). Briefly, in 96-well plates, lOpl/well of MTT was added at each time point and cells were incubated for 1 hour at 37°C in 5% CO2 atmosphere. Then, 100 pl/well of solubilization solution was added and formazan production was detected after an ovemight incubation at 37°C by spectrophotometric analysis at 570 nm.