FIG. 9.

Cellular IRF7 protein expression is induced by KSHV only in lytically infected cells. The photomicrographs show double-label immunohistochemical detection of cellular IRF7 protein only in infected PEL cells expressing lytic cycle viral proteins, but not in the majority of LANA1-positive latently infected PEL cells. (Upper left) Viral ORF-K8 (red nuclear chromogen) and cellular IRF7 (blue cytoplasmic chromogen) in untreated KSHV-positive BCBL1 cells; (upper right) ORF-K8 (red nuclei) and IRF7 (blue cytoplasm) in BCBL1 cells treated with TPA for 60 h; (lower left) IRF7 (red cytoplasm) and LANA1 (brown nuclei) in TPA-treated BCBL1 cells; (lower right) ORF-K8 (blue nuclei) and vIL6 (red cytoplasm) in TPA-treated BCBL1 cells.