Sensitivity of semiquantitative RT-PCR. Tenfold dilutions of B95.8 RNA were mixed with 1 μg of RNA from EBV⁻ K562 cells. Multiplex RT-PCR was performed using primer pairs specific for the β-actin cellular gene and either EBNA2, LMP1, LMP2A, or LMP2B gene. Hybridization was performed with radiolabeled probes specific for each gene. The lengths of the amplified products are shown on the left.