FIG. 4.

Titer of RSV-specific serum antibodies in BALB/c mice infected with rRSV/6120/mGM-CSF or rRSV/6120. The mice were mock infected (administered medium alone) or infected intranasally with the indicated dose (10⁴, 10⁵, or 10⁶ PFU per animal) of rRSV/6120/mGM-CSF or rRSV/6120 as part of the two experiments (1 and 2) shown in Fig. 3. Serum samples were collected 28 and 56 days later and analyzed for IgG specific to the F or G glycoprotein by glycoprotein-specific ELISA and for RSV-neutralizing antibodies using a 60% plaque reduction assay in the presence of complement. Mean titers are shown. Each ELISA titer is the mean (±SE) for eight animals, and the neutralization titers are the means for six to eight animals.