Effects of myxoma virus on established medulloblastoma cell lines in vitro. A, medulloblastoma (Daoy, ONS76, D341, D384, Ptc850, and Ptc1102) and murine fibroblast (NIH3T3) cell lines were infected with vMyxgfp or vMyxlac at a MOI of 5 and photographed 48h after infection. Middle, early viral gene expression (GFP) visualized by fluorescence microscopy. Inset, phase-contrast view of the same field. Right, late viral gene expression (β-galactosidase, blue foci) detected by X-gal staining. Magnification, ×100. Left, DV control. B, WST-1 assay comparing the effects of vMyxgfp on cell viability.