FIG. 1.

EBV reactivation induces morphological changes in cellular chromatin. EBV-positive NA or EBV-negative TW01 cells were not treated, were treated with TPA/SB, or were transfected with a plasmid expressing Rta. At 24 h postinduction or -transfection, cells were fixed and cellular DNA was stained with Hoechst 33258. (A) Cellular chromatin morphology of cells replicating EBV (NA, TPA, and Rta⁺), TW01 cells, and untreated cells. Arrowheads indicate cells with an altered DNA staining pattern observed among NA but not among TW01 cells. For each set, 300 cells were counted, and the experiment was repeated independently more than three times. (B) Cellular chromatin morphology of NA cells replicating EBV. Chromatin architecture of NA or TW01 cells treated with TPA/SB was observed by confocal microscopy. Condensed chromosomes and enlarged interchromosomal space were observed in EBV-replicating NA but not TW01 cells. (C) Cellular chromatin morphology of EBV-replicating Akata cells. EBV-positive (EBV⁺) or -negative (EBV⁻) Akata cells were induced for lytic virus replication by 0.5% (vol/vol) anti-human IgG (α-human Ig) cross-linking. At 24 h post-Ig treatment, cells were fixed and chromosome spread assays were performed as described in Materials and Methods. DNA and BGLF4 were then detected by staining with Hoechst 33258 and BGLF4 antibody. For each set, 150 cells were counted and the experiment was repeated twice. (D) Cell morphology of chemically induced or Rta-transduced NA or TW01 cells was visualized by immunostaining of actin filaments (e to h). Nuclear DNA (a to d) and BGLF4 kinase (i to l) were detected by Hoechst 33258 staining and immunostaining to indicate cells replicating virus.