Lethal Antibody Enhancement of Dengue Disease in Mice Is Prevented by Fc Modification
Figure 3
Detection and quantification of DV-infected cells with or without antibody-dependent enhancement.
Mice were administered naïve serum (NMS) or anti-DV1 serum and infected iv with 105 pfu DV2 the following day. Controls were mock-infected or infected with 107 pfu DV2 iv. A. Tissues were collected from all mice (n = 3–6 per group) at day 3.5, formalin-fixed, and processed into paraffin sections. Serial sections from each tissue were stained with anti-DV NS3 antibody E1D8 (NS3) or an isotype control mouse IgG2a (IgG2a data not shown), and multiple sections of each tissue type were thoroughly examined for staining. Positive staining for NS3 is brown while hematoxylin counterstain is blue. Strong cytoplasmic staining observed with E1D8, but not IgG2a control antibody, was considered DV-specific when observed in infected mice but not uninfected controls. NS3+ cells in lymph node, small intestine, and large intestine exhibited morphology and location consistent with tissue macrophages under all infection conditions (arrowheads). In liver, NS3+ cells were consistent with tissue macrophages and/or endothelial cells. Serial sections showed the F4/80 macrophage marker staining in the same locations where infected cells were present in lymph nodes, small intestine, large intestine, and bone marrow (data not shown). B. NS3+ cells per visual field were quantified. At least ten visual fields were counted for each sample except bone marrow, where four fields from four independent sections were counted due to the small area of mouse bone cross-sections. All pairwise comparisons were performed by two-sided Wilcoxon Rank Sum tests.