A Method for the Rapid Assay of Newcastle Disease Virus

Abstract

METHODS at present available for the detection and quantification of infectious Newcastle disease virus (NDV) particles include plaque assays^1,2, the development of haemagglutinating activity and/or death of fowl embryos³, the appearance of cytopathic effects⁴, and the enumeration of virus infected cells by fluorescent antibody staining⁵. With the exception of the last technique, all these methods require a minimum of 3 days for adequate evaluation. The adsorption of erythrocytes to infected cell monolayers as a means of detecting certain non-cytopathic myxoviruses⁶ suggested to us a method for titrating NDV. This communication reports an assay for infectious NDV based on the ability of this virus to initiate foci of haemadsorbing cells. Results from such a titration can be accurately determined 24 h after inoculation of the virus on to susceptible monolayers. The rapidity and reproducibility of this assay technique have made it exceptionally useful in our studies on the synthesis and properties of NDV.