Effect of Type-I IFN on Replication of Vaccinia Strains in Tumor and Normal Cell Lines

Abstract

<div><p>(A) Primary human cell lines (SAECs and NHBEs) were grown to 50% confluence in six-well plates and treated with human IFN-α (50 U/ml) either 24 h prior to or 5 h after infection with vaccinia (or else PBS was used as a control). Vaccinia strains WR (white bars) or <i>WR-delB18R</i> (WR with deletion of the <i>B18R</i> gene; black bars) were used at an MOI of 1.0 PFU/cell. After 72 h, viral titers in the wells were determined by plaque assay (Student <i>t</i>-test for WR versus <i>WR-delB18R</i> with IFN treatment postinfection, <i>p</i> = 0.0055 for SAECs and 0.0012 for NHBEs).</p> <p>(B) This assay was repeated using human tumor cell lines C33A, A2780, and HCT 116.</p> <p>(C) Serial dilutions of vaccinia strains were added to cells (NHBE or A2780) 5 h before addition of human IFN-alpha (or PBS) as before. Cell viability in the different wells was determined 72 h later by MTS assay, and EC50 values (viral PFU/ml required to reduce cell viability to 50% of untreated well) were determined.</p> <p>An asterisk (*) indicates significant difference (<i>p</i> = 0.0055 for SAECs and 0.0012 for NHBEs).</p></div