HPeV-1 internalization is inhibited in mouse cells lacking β1 integrin expression.

<p>(A) HPeV-1 internalizes into GE11-β1 but not GE11-KO cells. GE11-KO and -β1 cells were inoculated with HPeV-1 at a MOI of 5 on ice for 1 h followed by incubation for 6 h at 37°C. The cells were fixed, permeabilized, and stained with appropriate stains or antibodies as described in Materials and Methods. Actin filaments are shown in red, HPeV-1 in green and β1 integrin in blue. The β1 integrin expression on the cell surface was also analyzed by flow cytometry (right panel). (B) Clinical HPeV-1 isolates with low passage numbers (152231, 152478 and 452252) act similarly to the prototype. The cells were treated as in (A). (C) CV-A9 infects both GE11-KO and GE11-β1 cells. The CV-A9 infection was performed similarly to the HPeV-1 assay, followed by staining with anti-CV-A9 antibody (green) and DAPI (blue). Microscopic imaging was performed with Zeiss LSM780 confocal microscopy using a Plan-Apochromat objectives (63× / 1.2 oil/water [panels A and B] or with 40×/ 1.2. oil/water [panel C]). Bar 10 μm.