Figure 4.

CD169 Limits Dissemination of FVC into Erythroblast Niche of the Splenic Red Pulp

(A and B) Merged immunostaining images of splenic tissue sections from B6 and CD169^−/− mice 5 dpi after s.c. administration (2 × 10⁶ IU) of Ypet expressing FVC (green). B cells, erythroblasts, and metallophilic macrophages were identified using antibodies to surface markers B220 (blue), CD71 (red), and CD169 (pink), respectively. The B cell follicular area (white pulp) and extrafollicular erythroblast rich areas (red pulp) are demarcated by dashed white lines. Magnified images of merged and individual channels of insets are shown on the right.

(C) Merged immunostaining images of splenic tissue sections from B6 and CD169^−/− mice 5 dpi after r.o. administration of FVC (2,500 SFFU). Metallophilic macrophages lining the white pulp and FVC-infected cells were identified using antibodies to surface marker CD169 (red) and viral protein Glycogag (green).

(D) Electron tomography of a spleen section from CD169^−/− mice for an experiment as in (A). The image shows a cluster of clonally expanded FVC-infected erythroblasts (labeled E). Insets show details from serial tomographic reconstructions, demonstrating nascent viruses (red arrowheads) budding from the surfaces or invaginations of infected erythroblasts.

See also Figures S2 and S3 and Video S1. Scale bars as indicated.