KSHV and rKSHV.219 infection suppresses clonogenic colony-forming potential of CD34⁺HPCs in vitro. (A) CD34⁺ HPCs were infected with KSHV or with UV-irradiated KSHV (10 μW/cm²  for 1 hour). Cells were washed 3 times with PBS and plated in 2 mL MethoCult H4433 medium (3000 cells per 35mm × 10mm plate) in triplicate at 4 hours after infection. Colonies were visually scored and enumerated at 12 to 15 days after plating. Experiments were repeated 3 times using purified CD34⁺ HPCs from different donor tissues. The mean CFU-GM, BFU-E, HPP, and total colony numbers are presented. Statistically significant differences in the mean total colony numbers between KSHV and UV-KSHV (P = .021) groups were determined by single-tail ANOVA analysis. (B) CD34⁺ HPCs were infected with rKSHV.219, UV-irradiated rKSHV.219 (10 μW/cm²  for 1 hour), or heat-inactivated rKSHV.219 (65°C for 1 hour). Infected HPCs were washed and plated in MethoCult H4433 as described in panel A. Colonies were visually scored at 12 to 15 days after plating and used to calculate mean CFU-GM, BFU-E, HPP, and total colony numbers. Statistically significant differences in the mean total colony numbers between the rKSHV.219, UV-rKSHV.219, and HEAT-rKSHV.219 (P = 2.31 × 10^-6) groups were determined by single-tail ANOVA analysis. Experiments were repeated twice. Error bars represent standard error of the mean (SEM).