EBV gene expression in CD27⁺ memory B cells in high load allo-HSCT patients. Absolute numbers of EBV transcripts were quantified using a Q-PCR array. All data were first normalized to cellular PGK1 expression and then expressed relative to the levels of EBNA1 transcript. (A) EBV gene expression in CD27⁺ memory B cells sorted by FACS from patients 6, 9, and 12. (B) EBV gene expression in EBV-positive reference cell lines. CD+Oku LCL is a latently infected EBV-transformed B lymphoblastoid cell line characterized by activity of the Wp- and Cp promoters, and expression of EBNA1, EBNA2, LMP1, and LMP2 latent genes (a form of infection termed latency III). Rael-BL is a latently infected Burkitt lymphoma cell line which expresses a single latent gene EBNA1 transcribed from an alternative promoter Qp. Because both CD+Oku LCL and Rael-BL are tightly latent with only low-level expression of lytic cycle transcripts (exemplified by the immediate early gene BZLF1 and the late gene gp350), we also included a third reference line, AKBM Akata-GFP cells induced into lytic cycle by IgG crosslinking, to illustrate the much higher levels (typically >100-fold) of viral lytic gene transcription in productively infected cells.