Figure 1.
Expression of the US6 gene decreases cell surface expression of MHC class I molecules and prevents CTL recognition of virus-infected cells. US6 and control-transfected HeLaM cells (A) and PaLa cells (B) were analyzed for class I surface expression by flow cytometry using the mAb w6/32 and fluorescein-conjugated rabbit anti-mouse IgG. The control was a nonspecific isotype-matched monoclonal antibody. Peripheral blood mononuclear cells from an HLA-B8 positive donor were incubated in vitro with influenza A-infected cells and pulsed on day 8 with N380–88 peptide and feeder cells. On day 12 of bulk culture, CTL lysis was tested in a 51Cr release assay against Pala control (C) and Pala.US6-transfected (D) target cells, which were infected with influenza virus, pulsed with N380–88 peptide (10 μM), or untreated.