Use of a GFP-PML-expressing cell line as a biosensor for human cytomegalovirus infection

Human cytomegalovirus (HCMV) infection has a marked effect on promyelocytic leukemia (PML) bodies. Here, we describe a novel real-time monitoring system for HCMV-infected cells in vitro using a newly established cell line that stably expresses GFP-PML protein. Upon infection, HCMV causes specific dispersion of GFP-PML bodies, thereby allowing the infected cells to be monitored by fluorescence microscopy without immunostaining. Quantitative protocols using either an NPB fluorescence assay or a GFP-PML imaging assay are also described. The NPB fluorescence assay is rapid, sensitive, and sufficiently simple for screening of inhibitory reagents, while the GFP-PML imaging assay is highly sensitive and applicable to drug susceptibility testing of low-titer clinical isolates.