Rescue of bovine respiratory syncytial virus from cloned cDNA: Entire genome sequence of BRSV strain A51908

Infectious bovine respiratory syncytial virus (BRSV) was produced by intrac ellular co-expression of five plasmid borne cDNAs, each under the control o f a T7 RNA polymerase promoter. These separately encoded a full-length, gen etically-marked copy of BRSV antigenome along with either BRSV or human res piratory syncytial virus (HRSV) support plasmids, which express N, P, L and M2-1 proteins. HEp2 cells were used in transfection and recombinant vaccin ia virus (MVA-T7) provided T7 RNA polymerase to drive the transcription. Th e recovery of recombinant BRSV (rBRSV) was confirmed by immunological stain ing of plaques, restriction enzyme digestion and nucleotide sequencing of P CR fragments carrying the genetic markers from the rescued virus. The rBRSV was indistinguishable from its parental wild-type virus in its growth char acteristics in cell culture. The present work has completed the entire geno me sequence of BRSV strain A51908 (15,140 nt) and has also identified chang es in sequence and growth characteristics in cell culture from the original BRSV strain A51908 laboratory isolate.