CD40LG and infection: In this experiment, DENV is bound to an enhancing IgM (VDB33-IgM) and these DENV/Ig immune complexes are crosslinked to the BCR of polyclonal B cells using an anti-IgM secondary antibody (S6 Fig) and infection is assessed by intracellular DENV antigen with the pan-DENV mouse mAb 4G2.