Figure 4.

Activation and proliferation of DENV-infected B cells in vivo. (A) Frequencies of Ki-67⁺ naive (CD19⁺CD27⁻) B cells in healthy donors, DENV-negative febrile controls and dengue patients. (B) Concentrations of B-cell activating factor (BAFF) were analyzed in plasma of age-matched healthy donors, febrile controls and and patients with acute dengue infection. (C, D) CD19⁺ B cells from dengue patients were stained with B cell subset markers and anti-DENV NS3 antibody. Frequencies of (C) activated CD69⁺ and CD86⁺ and (D) proliferating Ki-67⁺ B cells within NS3⁻ and NS3⁺ populations of naive (CD19⁺CD27^-) and memory B cells (CD19⁺CD27⁺CD138⁻) from dengue patients. (E) Representative histogram to determining percentage of proliferated B cells upon stimulation with F(ab′)₂ anti-IgM antibody and CpG compared to unstimulated cells. (F) Frequencies of proliferated B cells isolated from healthy donors (n = 4) infected with or without DENV-2 reference strain in vitro followed by stimulation with F(ab′)₂ anti-IgM antibody and CpG for 6 days. For all panels, P-values were calculated using Mann–Whitney U test for comparing two groups. Bars and lines represent mean and standard deviation (SD). (*P < 0.05; ***P < 0.001; ****P < 0.0001).