Quantitative FISH of EBV and KSHV in PEL cells. (A) Example of a BC-2 cell assayed for EBV and a BCBL-1 cell assayed for KSHV by FISH. Shown is a single 0.35-µm z-plane of cells with signals detected by probes to EBV or KSHV. The intensities of raw signals were measured and summed in four to seven z-planes with CAPS. (B) The number of KSHV signals exceeded that of EBV measured in BC-2 cells (EBV, n = 66; KSHV, n = 24). (C) The signals of lower intensities were similar for both viruses; those of KSHV, however, extended to 10-fold higher values. The red lines indicate the medians for each of the distributions (EBV, n = 111; KSHV, 131). The two distributions in C differ as determined by the Kolmogorov–Smirnov test (P = 2.3 × 10^–5).