SARS-CoV-2 Protein and RNA Detection in Tissue Samples

Paraffin blocks from lungs and brain (ChP, cerebral cortex, globus pallidus, lateral ventricle, medulla oblongata, midbrain, pons, and putamen) were selected to produce a tissue microarray, as adapted from Pires et al. [17] (link). Four-µm sections were deparaffinized and rehydrated, subjected to antigen retrieval using 10 mM citrate buffer (pH 6.0) for 30 min at 98°C, and were then blocked/permeabilized (3% bovine serum albumin/0.3% Triton X-100) for 1 h. Overnight incubation at 4°C was performed with anti-SARS-CoV-2 SP monoclonal antibody (Genetex, Cat GTX632604, 1:500); convalescent serum (CS, 1:1000) or anti-dsRNA (J2) (Merck-Millipore Cat MABE1134, 1:200). The slides were then washed with PBS and incubated with secondary antibody (Goat anti-Mouse Alexa Fluor 488, 1:400; A-11001) for 45 min at 37°C. Nuclei were stained with 0.5 µg/mL 4′-6-diamino-2-phenylindole for 5 minutes, and the slides were mounted with Aqua-Poly-mount (Polysciences, Pennsylvania, USA). Images were acquired with a Leica TCS SP8 confocal microscope using a 63x/oil objective lens.