FIG. 4.

Plaque size formed by viruses. BS-C-1 cells were infected with the indicated viruses and incubated under semisolid overlay (DMEM containing 2.5% FBS and 1.5% carboxymethylcellulose) for 5 days. The monolayers were stained with 0.1% (wt/vol) crystal violet in 15% ethanol.