CD46 is an important factor for CMV infection and spread. a CD46 cell surface expression of wild-type ARPE-19 cells (Ewt), β2m Knock-out (KO) ARPE-19 cells (Eβ1), and three CD46-KO ARPE-19 cell clones (EC1, EC2, and EC3) was assessed by flow cytometry with mAbs against CD46 (2E7 and GB24), MHC class I (W6/32), and PY102 as a non-binding control. Following incubation with anti-mouse IgGAlexa647, the normalized cell number was plotted based on Alexa647 fluorescence intensity. b The respective KO cells (a) were subjected to anti-CD46 and GAPDH immunoblots. c ARPE-19 wt and CD46- and β2m-KO cells infected with TB40/E wt or AD169BADrUL131 were analyzed for infection by an HTI. Total number of infected cells was determined using anti-IE1 antibodies. d ARPE-19 wt and CD46- and β2m-KO cells infected with TB40/E wt, TB40/EMC UL99-eGFP, or AD169BADrUL131 were subjected to a plaque assay, counted 14 dpi. e Supernatant from Ewt, Eβ1, and EC2 cells infected (E: epithelial cells) with AD169BADrUL131 (MOI:0.1) from days 0–12 was added to MRC5 and analyzed for infection at 24 hpi using YFP fluorescent with a cytometer. The virus titre (infectious units (IU)/ml) was plotted for up to 12 dpi. f Cell lysates of wt HTR-8/SVneo (Twt) cells, β2m-KO HTR-8/SVneo (Tβ1) cells, and CD46-KO HTR-8/SVneo cell clones (TC1 and TC2, T: trophoblasts) were subjected to immunoblot using anti-CD46 and anti-GAPDH antibodies. g Cell lysates of AD169BADrUL131 (MOI:2) infected Twt, Tβ1, TC1 and TC2 were subjected to anti-IE1 and GAPDH immunoblots. h ARPE-19 wt and Tβ1, TC1, and TC2 clones infected with AD169BADrUL131 at varying MOIs were analyzed for infection by an HTI assay. The total number of infected cells was determined using a cytometer. i Representative cytometer images of (h) (overlay: Hoechst stain for nuclear stain (blue) and GFP expression (green) for virally infected cells) (MOI 2). The polypeptides and molecular weight markers are indicated for the immunoblots. Infection experiments (excluding westerns) were performed in triplicate. s.d. is depicted in the experiment. **P < 0.01, ***P < 0.001, ****P < 0.0001 (Student’s two-tailed t test)