A MICRO ASSAY FOR MOUSE AND HUMAN INTERFERON

Abstract

A simple micro assay for testing mouse and human interferon is described. The L‐F 1 line of mouse lung fibroblasts and the U‐line of human amnion cells were seeded in microtrays, treated with two‐fold dilutions of 0.1 ml interferon and challenged with Vesicular Stomatitis virus. Reading was done microscopically for presence of cytopathogenic effect and macroscopically for metabolic activity indicated by colour change. Sensitivity of the test is comparable to the commonly employed plaque reduction assay and the macro infectivity inhibition test. Reproducibility of the system is satisfactory. The interferon titres are influenced by the age and density of cells, length of interferon treatment and the dose of challenge virus. Age, density and length of treatment are standardized for the test and by means of a standard slope it is possible to adjust interferon titres to a standard challenge dose. The micro system is time saving, technically simple and allows testing of extremely small volumes of test material.