The plasmids encoded bovine respiratory syncytial virus (BRSV) N, P, M2, and L proteins are co-transfected into BSR T7/5, a BHK-derived cell line stably expressing T7 RNAP, and recombinant BRSV is reproducibly recovered from cDNA constructs after T7 RNAP-driven expression of
antigenome sense RNA (Buchholz et al., 1999).