Figure 3. Formation of large syncytia of primary human alveolar type II cells infected with HCoV-HKU1.
Cells were inoculated with a 1∶10 dilution of the clinical isolate HKU1/DEN/2010/21 at 34oC and fixed 120 hours post infection. Type II cell cultures were immunolabeled with polyclonal rabbit antibodies to purified HCoV-HKU1 spike protein and fluorescein labeled anti rabbit IgG (green). Nuclei were stained with DAPI (blue). Viral antigen is seen only within the cytoplasm of the cells. Efficient infection with cell to cell spread and formation of large, multinucleated giant cells is clearly evident.