FIG. 1.

Diagram of the genomic RNAs of two versions of rRSV expressing mGM-CSF, namely, rRSV/mGM-CSF and rRSV/6120/mGM-CSF. In each virus, a transcription cassette consisting of the mGM-CSF ORF under the control of RSV gene start and gene end transcription signals (upper box) was inserted into the XmaI site in the G-F intergenic region of rRSV. The start and stop codons of the GM-CSF ORF are in boldface, XmaI restriction endonuclease sites are in italics, and RSV gene start and gene end signals are underlined. The two viruses differ only in the SH gene of the respective rRSV backbones, as illustrated in the lower box. The backbone of the rRSV/mGM-CSF is that of the previously described wt rRSV (14) modified to contain an XmaI site in the G-F intergenic region (9). In the backbone of rRSV/6120/mGM-CSF, the SH gene was modified (i) to contain five translationally silent nucleotide substitutions in the last four codons of the SH ORF and (ii) to delete 112 nucleotides (nt; positions 4499 to 4610) of the complete antigenomic sequence) from the downstream nontranslated region of the SH gene (lower box). The XhoI and PacI sites used in the construction (Materials and Methods) are italicized and labeled, the SH gene end signal is underlined, the SH codons are shown as triplets, nucleotide substitutions are in lowercase, and the deleted sequence is boxed with the sequence positions indicated.