Cloning strategies for full-length cDNA of rLong and rLong-ΔG-EGFP. (A) Schematic diagram of rLong and rLong-∆G-EGFP full-length antigenomic cDNA, and the distribution of restriction enzyme sites within them. (B) The entire antigenome of long strain of RSV and RSV replacement were amplified as six fragments (A-F), and these fragments were assembled in the pBR322-Linker vector according to a certain order. the G gene was replaced with EGFP gene at fragment C (named as C1) to generate the complete cDNA clone of rLong-∆G-EGFP. (C) Schematic diagram showing the pBR322-Linker plasmid. The cassette comprising the T7 promoter, HamRz, seven site linker and HdvRz cDNA sequences, and the full length cDNA of rLong or rLong-∆G-EGFP was cloned into pBR322-Linker vector between restriction sites Sal I and Kpn I.