Fig. 2

Reactive microglia are involved in the HSV-1⁺ cell clearance and antigen presentation in moderately infected thalamus. a Representative flow cytometry plots for CD45⁺CD11b⁺ gate showing infiltrating immune cell populations (T cells represented in yellow, neutrophils in red, monocytes/macrophages in light pink) and microglia/microglial-like cell (in blue) in whole brain homogenates on day 0 (top) and day 6 p.i. (bottom). b Percentages of different immune cell populations, compared to all living single cells obtained from a whole brain on day 6 p.i. c Mice infected with HSV-1 showed reduced percentages of CD45⁺CD11b⁺CD115⁺ microglia/microglial-like cells in the thalamus on day 6 p.i. The results represent the means ± SEM for 3 mice per group at each timepoint. Statistical analyses were performed using an unpaired t test. Statistically significant results are indicated as follows: **P < 0.001. d, left) Immunofluorescence image of uninfected VPL (day 0) immunostained for TMEM119⁺ (green) CD68⁺ (red) shows surveillant microglia. d, middle) Immunofluorescence analyses of brain sections of moderately infected VPLs on day 6 p.i. show TMEM119⁺ (green) CD68⁺ (red) microglia/microglial-like cells gathering around HSV-1⁺ cells (pink). TMEM119⁺ ameboid microglia/microglial-like cells (white arrow) are visualized. d, right) Fluorescent microscopy image shows colocalized signals of TMEM119⁺ (red) microglia/microglial-like cells establishing a direct contact with CD3e⁺ (green) T cells (white circle). Nuclear staining was done with DAPI for both images. e HSV-1⁺ nanoparticles are specifically found within the endosome and at the membrane of microglia/microglia-like cells in SEM images of VPL on day 6 p.i. On the representative picture of HSV1-immunopositive microglia/microglial-like cells (e-1), the microglia/microglial-like cell are pseudocolored in red, and square boxes identify subcellular compartments. (e-2, 3). Insert at higher magnification shows nanogold particles within the (e-2) endosomes containing digested contains and (e-3) at the cellular membrane. Scale bars are equivalent to 5 μm at low magnification (e-1) and 1 μm at higher magnification (e-2, 3)