In this technology, researchers have engineered a modified version of Respiratory Syncytial Virus (RSV) strain A2 using reverse genetics to incorporate green fluorescent protein (GFP) into the first-gene position. This genetic modification allows for the efficient monitoring of RSV infection and the screening of potential chemical inhibitors. The GFP expression can be easily detected through fluorescence microscopy in live or fixed cells, providing a sensitive tool for both research and drug discovery. Importantly, placing GFP in the first-gene position minimizes interference with the expression of key RSV interferon antagonist genes, maintaining the virus's functionality while enhancing the brightness and utility of the GFP marker. This technology offers valuable insights into RSV infection dynamics and facilitates high-throughput screening for potential therapeutic agents.