RSV immunoplaque assay
RSV titres were assessed by immunoplaque assay. Lung homogenates were
titrated onto HEp-2 cell monolayers in 96-well plates. Twenty-four hours
later monolayers were fixed and permeabilised with 2%
H2O2 in methanol then bound with
biotin-conjugate goat anti-RSV antibody (BioRad; Watford, Hertfordshire,
UK). Plaques were visualised with extravadin peroxidase and AEC red
(SigmaAldrich; Glasgow, Scotland, UK) and infection units observed by
light microscopy.