Quantification of the Antiviral Effect of Interferon by Immunoassay of Vesicular Stomatitis Virus Proteins

Abstract

SUMMARYA simple solid-phase immunoassay for quantification of vesicular stomatitis virus (VSV) is described. Infected cultures are lysed with deoxycholate. Samples of the lysates are transferred to PVC immunoassay plates and the amount of virus protein adsorbed to the plates is then quantified by sequential incubation with antiserum against VSV proteins and 125I-labeUed Protein A. The decrease of VSV protein in interferon (IFN)-treated cultures is correlated with inhibition of formation of infectious virions; its quantification therefore allows accurate measurement of the antiviral effect. The applicability of the immunoassay for measuring the virus yield is not restricted to cells exhibiting a virus cytopathic effect. Moreover, since the decrease of virus protein is obtained at IFN concentrations lower than those that reduce cell killing by the virus, the assay provides a more sensitive measure for the IFN effect than that obtained by 'cytopathic effect inhibition' assays. While the nature of the virus function that IFN suppresses is very different for differing types of viruses, the cause for that suppression is, for many viruses, the same. It is a reflection of the fact that those virus proteins which carry out the functions are synthesized at reduced rates in the IFN-treated cells (Sonnabend & Friedman, 1973). A more direct and general approach for quantification of the antiviral effect should, therefore, consist of determining the level of virus proteins in the ceils rather than measuring activities which they display.In this study we describe a simple, solid-phase immunoassay for the proteins of vesicular stomatitis virus (VSV) and show that it can be applied for quantifying the effect of IFN on this virus. Comparison of this assay with a cytopathic effect assay showed that direct quantification of the decrease in viral protein is preferable to the secondary method of measuring viral cytopathy. Several applications of the immunoassay for the study of IFN have already been described elsewhere (Schattner et al., 1982a, b;Weissenbach et al., 1980;Wallach, 1982Wallach, , 1983Wallach et al., 1982).

Enzyme Immunoassay of Interferon with Peroxidase-labelled Virus-specific Monoclonal Antibodies

“…The latter can be measured by classical virological methods like plaque reduction or more recently with rather elaborate immunoassays using conventional antisera against vesicular stomatitis virus (VSV) or its proteins (Wallach, 1983;Shoham et al, 1984).…”

Interferon Deficiency Syndrome

“…At first these assays were carried out using human IFN sensitive fibroblasts from the MDBK bovine continuous cell line (Stewart, 1979), and later on human HeLa (H229) cells in culture. More recently we have employed an ELISA assay (Wallach, 1983), using an antiserum to VSV to measure the amount of viral protein in culture supernatants. The results of each assay are related to an International IFN standard (BRS 69/19) and are designated in units/ml.…”

Cloning and expression of mink (Neovison vison) interferon-γ gene and development of an antiviral assay

“…To investigate whether pre-treatment with mink IFN-γ could protect cells from virus infection, we analyzed antiviral activity using cytopathic inhibition assays in vitro (Wallach, 1983). Different extents of cytopathic effects caused by VSV were observed in MDCK cells pretreated with different concentrations of IFN-γ, viral replication was completely inhibited when cell hole was inoculated with 52.5 μg/ml 100 μl.…”