Validation of synthetic peptide enzyme immunoassays in differentiating two subgroups of ruminant respiratory syncytial virus.

Subgroup-specific peptide-based enzyme immunoassays from each respective G-glycoprotein of the ovine and the bovine respiratory syncytial virus (RSV) were developed to detect RSV-specific IgG responses in cattle. Antigenic peptides from the respective G-glycoprotein were identified from the extracellular central hydrophobic region (amino acids 158-189) located between 2 mucin-rich regions. These antigenic peptides identified by epitope mapping from each G-glycoprotein were synthesized and used to develop the subgroup-specific enzyme immunoassays. The negative cutoff for each enzyme immunoassay was established as the mean optical density of indirect immunofluorescent antibody-negative bovine sera plus 3 SDs. The sensitivity (82.9%) and specificity (100%) of the bovine enzyme immunoassay and the specificity (95.8%) of the ovine enzyme immunoassay were determined by comparison with indirect immunofluorescence (used as the "gold standard"). The negative and positive predictive values were calculated for each assay. The presence of serum antibody to ovine RSV in cattle implies that this virus infects cattle and may contribute to the pathogenesis of bovine respiratory disease.