Figure 2.

Recovery of infectious recombinant RSV entirely from cloned cDNAs. The five cDNAs are indicated by shaded rectangles and encode a positive-sense copy of the viral genome (antigenome) and mRNAs for the N, P, L, and M2-1 proteins of the nucleocapsid/polymerase complex. Expression of the cDNAs is under the control of a promoter for bacteriophage T7 RNA polymerase (T7pr). The plasmid backbones that bear the cDNAs are not shown. The indicated ribozyme encoded at the downstream end of the antigenome executes self-cleavage to produce a correct 3′ end. The T7 RNA polymerase can be provided intracellularly using one of the three indicated strategies.