Fig. 2. Detection of EBV in EBV-positive and -negative Mutu cell clones. (A) Southern blot analysis of EBV genomes. DNA samples (5 µg each) were digested with BamHI, and the blot was probed with the BamHI C fragment of EBV DNA. (B) PCR analysis of EBV genomes. DNA samples (100 ng each) were amplified with primers for EBER1 and BamHI W regions. (C) Immunoblot analysis for detection of EBNAs and LMP1. The blots were probed with EBNA-positive human serum (upper blot) and an anti-LMP1 monoclonal antibody (lower blot). Protein samples extracted from 105 cells were loaded per slot. (D) RT–PCR analysis of EBNA promoter usage and EBV latent gene expression. Akata cells were used as a positive control for detection of Qp-initiated EBNA mRNA, and a lymphoblastoid cell line immortalized by Akata EBV (LCL) was used as a positive control for detection of Cp- or Wp-initiated EBNA mRNAs and BARF0, LMP2A and LMP2B mRNAs.