Detection and quantitation of Newcastle disease virus proteins in infected chicken embryo cells

A technique was analyzed by which Newcastle disease virus (NDV) proteins could be quantitatively detected in the presence of chicken embryo cellular proteins in NDV-infected cells. The technique involved removal of electropho-proteins from a sodium dodecyl sulfate-polyacrylamide-agarose gel matrix by chemical cleavage of the acrylamide gel cross-linker. The proteins were subsequently transferred and covalently bound to diazobenzyloxymethyl paper. By incubating the paper with unlabeled antisera and 125I-labeled Staphylococcus aureus protein A, the specificity of the antisera and the sensitivity of this method of quantitative antigen detection were tested. The results demonstrated that as little as 1 ng of an individual NDV protein could be detected. Furthermore, this technique can simultaneously quantitate the synthesis of multiple NDV proteins under experimental conditions in which immunofluorescence, hemadsorption, and plaque assays failed to show virus protein synthesis or the formation of virus progeny.