BSR T7/5 cells represent a foundational advancement in virology, offering a robust platform for the recovery of RNA viruses via reverse genetics. Established over 20 years ago, these cells have proven instrumental in the recovery of a wide array of RNA viruses, particularly those belonging to the mononegavirales order. By enabling the insertion of antigenome sequences into cDNA plasmids under a T7 RNA polymerase promoter, BSR T7/5 cells facilitate the transcription of RNA antigenomes and mRNA encoding RNP elements, leading to the assembly of infectious viruses. Notably, this system does not require helper viruses, and the cell line's permissiveness, attributed to the absence of a functional type 1 interferon response, makes it especially valuable for viruses replicating in the cytoplasm.