Detection of IgE antibodies to bovine respiratory syncytial virus.

The role of IgE antibodies against respiratory syncytial virus has attracted attention for both human and bovine disease. To detect such antibodies, we have developed an enzyme-linked immunosorbent assay (ELISA) specific for bovine respiratory syncytial virus (BRSV). Firstly, antiserum strongly positive for BRSV-specific IgE was produced by immunizing a levamisole-treated calf with BRSV. The presence and specificity of BRSV-specific IgE in this animal was confirmed with the Praunitz-Kustner (PK) technique. Potential interference in an ELISA by other BRSV-specific immunoglobulin isotypes was eliminated by preferential precipitation of serum samples with 27.5% saturated ammonium sulfate. The correlation between the PK and the assay was greater than 93% and the ELISA was found to be more specific than the PK. Indeed, in a pilot experimental infection study, the serum levels of BRSV-specific IgE were found to correlate with the symptom expression following repetitive live virus aerosolization. This may prove to be a useful rapid test to study both herd immunity and the potential pathogenic influence of IgE.