FIG. 1.

Northern hybridization of BC-1 mRNA with ORF72 (A), ORF73 (B), ORF K13 (C), and ORF 25 (D) probes. Probe hybridizations for mRNA from uninduced BC-1 cells (lane 1), BC-1 cells treated with 20-ng/ml TPA for 48 h (lane 2), BC-1 cells treated with 0.5 mM PFA (lane 3), BC-1 cells treated with both 20-ng/ml TPA and 0.5 mM PFA (lane 4), and KSHV-negative, EBV-infected P3HR1 cells treated with 20-ng/ml TPA (lane 5) are shown. ORF72 (vCYC) (panel A) and ORF K13 (vFLIP) (panel C) probes hybridize to both the 6.0-kb LT1 and the 2.0-kb LT2 bands while only the 6.0-kb LT1 band hybridizes with the ORF73 probe (panel B). A low-abundance 1-kb band is detected with the ORF72 probe alone (panel A). LT1 and LT2 bands are not induced by TPA and are not inhibited by PFA treatment, consistent with their designation as class I or latent viral transcripts (40). P3HR1 mRNA does not cross-hybridize to any of the KSHV probes. (E) The same as the blot shown in panel A except it has been stripped and reprobed with a β-actin probe to control for equal loading.