B. Each photo depicts an immunofluorescence assay using either no primary antibody, or the primary antibody indicated below it (Myc, 2B2, 1A9, 4B12, or 1G10). Immunofluorescence assay results of COS7 cells expressing Myc-tagged HBcAg (top photos) or a Myc-tagged fragment (aa1048–1206) of SARS-CoV-2 S protein (bottom photos) using the indicated primary antibodies, followed by Alexa Fluor 488-conjugated secondary antibody (green) are shown. Cell nuclei were counterstained with DAPI (blue). Scale bar = 50 µm.