Effect of GFP-EH21 on the yields of cell-associated and released virus. BS-C-1 cells were infected with 5 PFU per cell of vEH21i with (+) or without (−) IPTG, WR, IHD-J, vWEH21, or vIEH21 as indicated. After 24 h the medium and cells were harvested separately, and the amount of infectious virus in each was determined by plaque assay. Means with standard deviations from three separate infections are shown.