Chronic LCMV-cl13 directly infects endothelial cells, CARcs, and mature hematopoietic cells. (A and B) Quantification of the cellular density of LepR-Cre/tdTomato⁺ CARcs in the BM of uninfected mice (CTRL) and 7 dpi with LCMV-cl13 (n = 6 mice per group). Statistics were analyzed by two-tailed Mann–Whitney U test with **, P < 0.005. Representative images in which cells quantified are marked by yellow spheres are shown in B; scale bars, 100 µm. (C) Maximum-intensity projection of a representative femoral cavity 7 dpi with LCMV-cl13. White signal shows transmitted light (bone outline); blue, CD105 (BM sinusoids); red, VL4 (actively replicating LCMV-cl13 particles), and green, CXCL12-GFP (CARc). Scale bars, 2 mm (left, whole femur); 400 µm (middle, whole diaphysis); 50 µm (right, zoomed image). Arrows indicate infected GFP⁺ CARcs. (D) Representative dot plots for intracellular staining for viral nucleoprotein using VL4. Percentages of LCMV-cl13–infected cells in the BM 7 dpi are shown for LSKCD48⁻CD150⁺ HSCs (orange), erythroid progenitors (red), BM endothelial cells (blue), and BM CARcs (green), respectively. Levels of specific isotype control stainings for each population are shown in overlaid dark plots. FSC, forward scatter; MEP, megakaryocyte-erythroid progenitor cell.