Epstein-Barr virus (EBV) gene expression in lymphoid B cells during acute infectious mononucleosis (IM) and clonality of the directly growing cell lines.

We examined the patterns of viral gene expression in acute infectious mononucleosis (IM) patients and the clonality of the directly growing EBV-carrying cell lines. Both low- and high-density EBV-carrying B cells obtained from the patients' tonsils expressed EBNA1, EBNA2 and LMP1. Like LCLs and immunoblastic B-cell lymphomas, the in vivo EBV-carrying low-density cells used only the latency III program for viral gene expression. The in vivo EBV-carrying high-density B cells used both the latency I program, as indicated by the QUK-, and the latency III program, as indicated by the YUK-EBNA1. This suggests that the lymphoid tissues contained not only proliferating immunoblasts but also cells programmed for latent viral persistence in vivo. EBV-carrying cells that grew directly into permanent cell lines in the presence of virus-neutralizing antibody and a late viral inhibitor were polyclonal, as indicated by JH rearrangement. Two of the high-density-derived lines had identical JH and TR patterns, indicating a common parental origin. Our investigation indicates that EBV-carrying cells divide and survive in a fully competent immune system during the outbreak of acute IM.