Fig 1A shows that in mock-treated slices, no pan-flavivirus labeling was observed, whereas USUV-infected samples showed strong pan-flavivirus staining, indicating an efficient USUV infection. Co-labeling with neuronal- (NeuN), astrocyte- (GFAP) and microglial- (Iba1) specific antibodies with the pan-flavivirus antibody showed a broad tropism of USUV for brain cells (Fig 1B and 1C). Here, GFAP is linked to infection.