EBV latent gene expression in PEL cells superinfected with the recombinant EBV. Proteins were separated on 7.5% SDS-polyacrylamide gels. EBNAs were detected with a polyclonal serum. LMP1 was visualized by CS1-4 monoclonal antibodies. Akata virus–derived LCL was used as a positive control. EBER-1, LMP2A, and LMP2B were detected by RT-PCR. (A) BC-3; (B) CRO-APO/6, and (C) CRO-APO/3 and their respective EBV-infected clones. A mixture of CS1-4 and PE2 was used to detect LMP1 and EBNA-2 in CRO-AP/3 convertants.