Fig. 7: T- and B-cell accumulation in brain of SARS-CoV-2-infected K18 hACE2 transgenic mice.

Normal brain shown at 2 DPI (a, b). Incremental mononuclear infiltrates were noted histologically at 4 (e, f) and 6 (i, j) DPI. There was CD3 cytoplasmic immunolabeling of rare round cells morphologically consistent with lymphocytes in the brain 2 DPI (c). Incremental meningeal, intra-parenchymal, and perivascular CD3-positive cells were observed in the brain of 4 (g) and 6 (k) DPI. Brain of 2 (d) and 4 (h) DPI were mostly negative for CD20. CD20-positive cells were rare at 6 DPI (l). The outer margins of vascular structures and in some occasions the collagenous connective tissue of the meninges exhibited non-specific staining. The brain of 2 and 4 DPI mice had rare individual intra-parenchymal CD3 cells, some of which were not morphologically consistent with round cells. Tissue time points and staining as Fig. 6. Representative images of n = 6 (three males and three females per time-point and group) randomly chosen. Scale bars left images, 1 mm. Scale bars right images, 50 μm. Data are representative over two independent experiments.