Respiratory syncytial virus (RSV) is the leading cause of upper and lower respiratory tract infections in infants and young children. Preclinical therapeutic studies require simple readouts for viral replication (e.g. readouts for high throughput screening of compound libraries). Researchers at Nationwide Children's Hospital and the NIH have constructed a recombinant RSV that expresses both green fluorescent protein (GFP) and Renilla luciferase that in turn allow for rapid quantifiable real time readout of virus replication or titer. In addition, the RSV virus is constructed with a G glycoprotein mutation that could reduce false positive hits during compound library screens.