PRMT5 inhibition prevents EBV-driven B-cell immortalization. (A-B) Purified normal B cells were infected with EBV and cultures were exposed to either lentivirus expressing PRMT5-specific siRNA or scramble RNA control. PRMT5 expression was assessed by confocal microscopy, and cell proliferation was assessed by uptake of [³H]-thymidine and flow cytometry. (C) Purified normal B cells were infected with EBV and, at various time points (days 4, 7, 14, and 21), cultures were exposed to DMSO, highly selective PRMT5 inhibitor (CMP5, 40 µM), or nonreactive control small-molecule CMP6 (40 µM). The effect of PRMT5 inhibition on EBV⁺ B-cell outgrowth was measured by absolute numbers of CD19⁺ cells over 35 days. *P < .05. Error bars indicate SEM.