HeLa cells (American Type Culture Collection) were grown and maintained in complete medium [Dulbecco's modified Eagle's media (DMEM) supplemented with 10% heat-inactivated newborn calf serum (NCS) (Invitrogen)]. CVB3 (Kandolf strain) was propagated in HeLa cells and stored at 280uC. Virus titer was routinely determined by a plaque assay prior to infection as described below.