Microplaque immunoperoxidase detection of infectious respiratory syncytial virus in the lungs of infected mice

A rapid microplaque technique was developed for the detection of infectious respiratory syncytial virus (RSV) in the lungs of infected mice. Infected lung homogenates were titrated on microwell HEp-2 monolayers and incubated for 24 or 48 h. The microwells were then fixed with 4% formaldehyde in saline, or methanol containing 0.5% hydrogen peroxide. 24-h single cell infectious foci and 48-h microplaques were detected by an indirect immunoperoxidase (IIP) assay using monoclonal antibodies specific for RSV envelope glycoproteins as the first layer. This method can be used for the quantification of lung RSV in large numbers of samples much more rapidly and economically than conventional plaque assay techniques. In addition, the use of the IIP assay renders the system specific for RSV.