UL141-mediated downregulation of cell surface CD155 detected by flow cytometry. Flow cytometry with mAb D171 of cell surface CD155 on mock-infected cells or cells after infection with HCMV strains AD169 (UL141−) or Toledo (a), after infection with TB40E-Bart (UL141−) or TB40E-Lisa (b), after infection with adenovirus vectors encoding UL141 or UL16 (c), and in continuous cell lines expressing UL141-GFP or UL16-GFP fusion proteins (d). Dotted lines, staining with an isotype-matched control antibody. mIgG, mouse IgG.