Figure 3.

The HCMV particle mediates the induction of differentially expressed HF RNAs. (A) Requirements for induction monitored by Northern blot assay. The relative amounts of three cellular RNAs (cig1, cig6, and cig49) were monitored in mock-infected cells (mock), HCMV AD169-infected cells (HCMV), cells treated with medium from which virions were removed by filtration (inf. med.), mock-infected cells treated with cycloheximide (CX), HCMV AD169-infected cells treated with cycloheximide (CX+HCMV), cells infected with purified HCMV AD169 particles (virions), cells infected with purified noninfectious enveloped particles from HCMV AD169 (NIEPs), adenovirus-infected cells (Ad dl309), herpes simplex type 1-infected cells (HSV-1), HCMV Towne-infected cells, HCMV Toledo-infected cells, interferon α-treated cells (IFN-α), and cells treated with interferon that was added to medium and passed through the filter type used to exclude virus (fil. IFN-α). (B) Northern blot assay showing that antibody that neutralizes HCMV (antibody C) blocks the induction of cig RNA accumulation, whereas antibodies that neutralize interferon α or β (antibody Iα, Iβ) block the induction of cig RNAs by interferon α or β (inducer Iα, Iβ) but have no effect on the induction of cig RNAs by HCMV (C). RNA prepared from mock-infected control cells is designated M. The cellular cytosolic phospholipase A2 RNA was assayed as a loading control (control, cPLA2).