Quantification of Respiratory Syncytial Virus by Immunostaining Plaque Assay

A useful and reproducible method to determine infectious respiratory syncytial virus (RSV) is to quantify virus plaques using immunostaining of infected Vero E6 cells. Immunostaining, in lieu of counterstaining, allows for accurate detection and quantification of RSV-specific plaques, avoiding spurious and nonspecific results. This method is important because RSV plaque morphology can be atypical in susceptible cell lines and often varies because it is a function of virus replication, cytopathic effect, and viral fitness. This protocol describes determining RSV titers using an immunostaining plaque assay on Vero E6 cells.