Recombinant green fluorescent protein-expressing human cytomegalovirus as a tool for screening antiviral agents

A recombinant human cytomegalovirus (AD169-GFP) expressing green fluorescen t protein was generated by homologous recombination. Infection of human fib robtast cultures with AD169-GFP virus produced stable and readily detectabl e amounts of GFP signals which were quantitated by automated fluorometry. H ereby, high levels of sensitivity and reproducibility could be achieved, co mpared to those with the conventional plaque reduction assay. Antiviral act ivities were determined for four reference compounds as well as a set of pu tative novel cytomegalovirus inhibitors. The results obtained were exactly in line with the known characteristics of reference compounds and furthermo re revealed distinct antiviral activities of novel in vitro inhibitors. The fluorometric data could be confirmed by GFP-based flow cytometry and fluor escence microscopy. In addition, laboratory virus variants derived from the recombinant AD169-GFP virus provided further possibilities for study of th e characteristics of drug resistance. The GFP-based antiviral assay appeare d to be very reliable for measuring virus-inhibitory effects in concentrati on- and time-dependent fashions and might also be adaptable for high-throug hput screenings of cytomegalovirus-specific antiviral agents.