Regulation of MHC-I by KSHV transcripts. (A) Histograms showing the levels of MHC-I expression in LECs expressing 6 KSHV genes. Geomean fluorescence is shown at the upper right corner of each histogram. The results from 2 independent screens are also shown (bar graphs). vMIR1 was used as a control for MHC-I down-regulation. MHC-I levels were determined 3 days after infection. (B) RT-PCR confirming expression of viral transcripts in LECs infected with the lentiviral constructs used for the screen. Second column shows the non-RT controls for each gene. GAPDH was used as a housekeeping control gene. (C) qRT-PCR analysis of KLECs (3 days after infection) for expression of GAPDH, LANA, vFLIP, vIRF1, vMIR1, vMIR2, and ORF26 in KLEC (♦) and purified by cell sorting (4 days after infection) GFP-expressing KLEC (). Ct values (y-axis) indicate the cycle number where PCR products become detectable. Lower Ct values correspond to higher average mRNA expression.