Sensitivity of DNA-PCR for EBNA2 gene detection. Tenfold serial dilutions of DNA from EBV⁺ B95.8 or AG876 cells were mixed with 1 μg of DNA from EBV⁻ K562 cells and PCR amplified with EBNA2 primers. The amplified products, of 169 bp and 185 bp for EBV types 1 and 2, respectively, were visualized with a radiolabeled probe that detects EBV type 1 (A) and type 2 (B). Regression curves (C and D) were obtained as described in Materials and Methods.