FIG. 4.

Plaque progression in MDBK cells infected with HSV-1 [V44]. MDBK cells grown in a six-well dish were infected with 2,000 PFU of HSV-1 [44]. Single plaques were ringed at 24 h postinfection with a marker objective, and plaque progression in individual plaques was monitored every day for 12 days by confocal microscopy on live cells. Typical results are shown. Images were taken at 2 (a), 4 (b), 6 (c), and 10 (d) days after infection, with the same microscope settings for imaging by phase contrast and by GFP fluorescence. After 10 days, the medium in the dish was replaced with fresh medium, and the cells were imaged 5 days later (e).