LZ1EBV(+) B-cell clones have percentages of capped cells and virus copy numbers per cell similar to those of wt EBV(+) B-cell clones. Two and three independent clones infected with wt EBV or LZ1EBV, respectively, were fixed, permeabilized, stained with rabbit anti-LMP1, and detected with Texas red-conjugated anti-rabbit antibody. The percentage of cells that had cap-like structures formed by LMP1 was determined. In both B-cell clones, approximately 7% of the cells formed a cap-like structure of LMP1. FISH analysis was performed to determine the average virus copy numbers in B-cell clones. Four wt EBV(+) clones and five LZ1EBV(+) clones were tested, and on average, 10 cells were counted per clone. There was no difference in the average virus copy numbers per cell. 721 cells were used as a positive control.