ICP22 and VP16 co-regulate transcription of HSV-1 gene promoters and viral proliferation.

<p>(A) The transcriptional regulation of HSV-1 α-, β- and γ-gene promoters by ICP22 and VP16. CHO-K1 cells were co-transfected with the reporter plasmids (pGL-α4, TK, gC, or VHS) and the effector expression plasmids (pcDNA-ICP22 and/or pcDNA-VP16) as indicated for 36 h, each group took transfection of pcDNA3 as a control. The cell lysates were analyzed by the dual luciferase assay and normalized with the renilla luciferase expression. (B, C) Increasing the expression levels of ICP22 and VP16 affects viral proliferation and α-gene expression. Hep-2 cells were co-transfected with ICP22, VP16 expression plasmids as indicated (pcDNA3 as control), all transfections were balanced to a total equal amount of DNA with pcDNA3. At 30 h post-transfection, the cells were infected with HSV-1 at MOI of 1.5 (B) or MOI of 10 (C). At 4 h post-infection, total RNA was extracted from the cell lysates (C) and subjected to quantitative RT-PCR to measure the RNA level of viral ICP4 and ICP0 segments with β-actin RNA serving as an internal control. At 20 h post-infection, the medium from Hep-2 cells (B) was collected to measure the virus titer by microtitration assay. Error bars represent the standard deviation from triplicate samples. * P<0.05 by student's t-test.