Viral replication
L929 cells were infected at an MOI of 0.1 or 20 in DMEM containing 2% FBS. Forty-five minutes post-infection, medium was removed and cells were washed with phosphate-buffered salinę (PBS) and fresh DMEM 2% FBS was added. At each time-point, supematants were harvested and titers were determined by plaque assay on Vero cells as described previously (Desforges et al., 2001).