FIG 5.

In situ immunofluorescence (IFA) in tissues of SARS-CoV-2 D614G, Delta, and Omicron BA.1.1 inoculated cats. Tissues were subjected to IFA using a monoclonal antibody against nucleocapsid protein (NP) of SARS-CoV-2. Nasal turbinate, trachea and lung were collected from SARS-CoV-2 D614G (B.1), Delta (B.1.617.2), and Omicron (B.1.1.529) inoculated cats on days 3, 5, and 14 postinfection (pi), and on day 14 pi from controls (mock inoculated). Note, intensive labeling of NP (Green) on the tissues from D614G-, and Delta-infected cats, while trace amount of staining on tissues from Omicron-infected animals. Nuclear counterstain was performed with DAPI (Blue) (A). In addition to above-described tissues, palate/tonsil, retropharyngeal lymph node, and heart were evaluated. IFA scores (established as described in Materials and Methods) for the tissues evaluated on days 3, 5 and 14 are presented in (B), (C), and (D), respectively.