Fig. 2: IFN-I response restricts viral infection in meninges and ChP.

a OPT-MRI mapping viral infection in the ventricles from OPT signal (red) onto the OCUM template (grey) (n = 5). b Confocal images of cortical slices showing meninges (yellow arrowheads) and endothelial cells (red arrowheads) immunolabeled with anti-NS5 antibody (green). Scale bars = 100 µm. c LSFM showing high-resolution image of the fourth ventricle ChP infected with LGTV, from a representative brain. (i) Tissue orientation during image acquisition. Illustration was created using BioRender.com. (ii) Volumetric 3D render of LSFM of LGTV infected fourth ventricle ChP, immunolabeled with anti-NS5 antibodies (red glow). z = 2000 µm; scale bar = 300 µm. Solid-line square indicates the area imaged and dashed-line shows the orientation of iii. (iii) Tomographic section, YZ plane, z = 600 µm. d Confocal images of the fourth ventricle ChP (asterisk). Brains were immunolabeled with anti-NS5 (green), anti-TUBB3 (red) for mature neuron and DAPI for nucleus (blue). Scale bars = 100 µm. e Maximum intensity projection capturing fourth ventricle ChP, immunolabeled anti-NS5 (green) and anti-AQPI (red) for ChP epithelial cell. Scale bars = 20 µm. f Ultrastructure of virus replication complex in ChP epithelial cells (indicated by cilia on the apical side; arrowheads) of Ifnar^–/– brain by electron microscopy. Low-magnification TEM image of a heavily infected cell indicated by dilated ER membrane. Scale bar = 5 µm. g High-magnification TEM of f. Scale bar = 1 µm. Insets show high magnification images of (i) virus particles and (ii) replication complexes. Scale bar = 200 nm. h–j FIB-SEM volume imaging shows viral replication complexes within dilated ER. Scale bar = 500 nm. i Segmentation image created from the 3D volume images in h. Scale bar = 500 nm. j Slice-through volume image of two infected cells (blue and green). Scale bar = 1 µm. Inset shows different z depths of the same volume. Boxes i-iii show apparent released virus particles (arrowheads) between the cilia. Scale bar = 100 nm. The confocal images n = 3/genotype; 2 slices/brain, and the EM images n = 2 brains; 3–5 technical replicates. Animations of Fig. 2c and i are shown in the Supplementary Movies 2 and 3.