FIG. 2.
(A) Organization of the genome of BAC20 and its BamHI restriction map. An overview of the organization of the UL44 locus with the two predicted promoters is given. A PCR product of a kanamycin resistance gene (aphAI) flanked by 50-bp sequences homologous to target sequences was used to replace UL44 via Red mutagenesis. After DNA transfection, gC-deficient virus was reconstituted. The positions of terminal long and short repeats (TRL and TRS), unique long and short regions (UL and US), and inverted long and short repeats (IRL and IRS) are indicated. (B) Plaque sizes of the gC-negative virus (v20kanΔgC) were compared to those of parental v20. One-hundred plaques each were photographed with a fluorescence microscope (Zeiss Axiovert 25) and a digital camera (Zeiss Axiocam) and measured with the ImageJ software after staining with an MDV-specific antiserum. Means and standard deviations (error bars) are given. (C) Multistep growth kinetics of 20kanΔgC virus and v20 were determined in triplicate. Means and standard deviations (error bars) are given.