FIG. 7.
UV-inactivated HCMV virions applied at a high viral-particle/cell ratio greatly increase the ability of rΔ-300/-579 to produce plaques at low MOI. Purified WTUV (3 to 5 PFU/cell prior to UV inactivation) was applied at the time of infection of HFF cells with WT or rΔ-300/-579 at an MOI of 0.001. After viral absorption, cells were washed and covered with agarose. Viral plaques were visualized by light microscopy and enumerated. Mean plaque numbers and SDs were derived from triplicate experiments performed in parallel.