Fig. 3. EBV expression in EBV-positive and -negative Akata, Daudi and Mutu cell clones. (A) Immunoblot analysis for detection of EBNAs and LMP1. The blots were probed with EBNA-positive human serum (upper blot), an anti-EBNA2 monoclonal antibody (middle blot) and an anti-LMP1 monoclonal antibody (lower blot). Protein samples extracted from 105 cells were loaded per slot. (B) 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 EBER, BARF0, LMP2A and LMP2B mRNAs.