FIG. 3.

Pharmacologic induction of KSHV lytic gene expression. (A) Expression of the T1.1/nut1 lytic gene transcript in JSC-1 and BCBL-1 cells with and without TPA or butyrate lytic inducing agents. Cells were treated with TPA (20 ng/ml) or butyrate (1 mM) for 36 h. Data represent positive stained cells, as determined by in situ hybridization with a T1.1 riboprobe. More than 10 fields of cells (>100 cells per field) were counted for each sample. (B) Immunohistochemical staining shows vTK expression in occasional JSC-1 cells in the absence of induction. (C) Following butyrate treatment, expression of vTK was detected in many more cells. (D) Immunohistochemistry for EBV-encoded lytic antigen ZTA in butyrate-treated JSC-1 cells shows no antigen expression. (E) ZTA expression shown for B95-8 control cells confirms positive ZTA antibody staining. An alkaline phosphatase detection system with a hematoxylin counterstain was used. Magnification, ×250.