Serum anti-BRSV IgG
in calves, before and after aerosol challenge with either BRSV-Snk or BRSV-Dk. Calves were experimentally infected as described in Figure 1. BRSV-specific IgG1 antibodies, detected by ELISA (SVANOVIR® BRSV-Ab ELISA, Boehringer Ingelheim Svanova, Sweden) in serum diluted 1:25, are expressed as percent of the corrected optical density (COD) of a positive control sample. The shaded area of the chart indicates ≤10% COD of positive, defined as negative by the kit manufacturer.