FIG. 1.

(A) Insertion of a transcription cassette encoding murine IL-4 into the RSV genome. A cDNA of the IL-4 open reading frame was engineered to be flanked by RSV-specific gene start and gene end transcription signals. It was inserted into a cloned cDNA of the RSV antigenome at an XmaI site that had been engineered into the intergenic region between the viral G and F genes (8). (B) Comparison of growth kinetics of wt RSV, RSV/IL-4, and RSV/CAT in HEp-2 cells (multiplicity of infection, 2 PFU).