Fig. 4.

Characterization of DENV antibodies elicited after DENV primary or secondary infection and role of B lymphocytes in DENV secondary infection. (a) IgG anti-DENV-1 E, (b) IgG anti-DENV-2 E and (c) neutralization (PRNT₅₀) against DENV-2 in sera from DENV-1 and DENV-2 i.p. infected C57BL/6 mice. (d) IgG anti-DENV-1 E and (e) IgG anti-DENV-2 E in sera from DENV-1, cell supernatant (placebo) or DENV-2 i.p. infected mice, challenged i.p. with DENV-2 at day 60 p.i. Arrows indicate DENV-2 challenge at day 60 p.i. (f–l) C57BL/6 mice were infected f.p. with DENV-1, DENV-2 or cell supernatant (placebo), resected of the ipsilateral popliteal lymph nodes 4 days later (DENV-1r, DENV-2r) and challenged with DENV-2 i.p. 60 days post-primary infection. (g–l) Hematological and biochemical parameters at different times post-secondary infection with DENV-2 (0, 4, and 7 days). ALT: alanine aminotransferase; AST: aspartate aminotransferase; ALP: alkaline phosphatase; CK: creatine kinase; LDH: lactate dehydrogenase. Values represent means ± SEM (n = 4–6/group). Two independent experiments were performed that showed similar results. NS, non-significant, *p < 0.05, **p < 0.01, ***p < 0.001, determined by (a, b) Student's un-paired t-test or (c–e, g–l) one-way ANOVA (dashed line) and Bonferroni's multiple comparison post-test (solid line). (g–l) p = NS for all DENV-1/DENV-2 vs. DENV-1r/DENV-2 groups.