Nested PCR screening and probe hybridization for BZLF1 (B), BRLF1 (C), BALF2 (D), and BcLF1 (E) in RNA preparations from freshly prepared and enriched B cells of IM patients. RNA from 2 × 10⁶ cells was used as a template. Before the EBV-specific PCR, RNA quality was controlled by histone 3.3 RT-PCR (A).41 Positive controls were performed with 2 × 10⁴ PMA-treated P3HR1/16 cells for BRLF1 and 2 × 10⁶ untreated B95-8 cells for BZLF1, BALF2, and BcLF1 RT-PCR and nested PCR. For negative controls, we used 2 × 10⁶ EBV-negative BJAB cells.