Humanized mAb against Dengue Virus www.plosntds.org (Jackson ImmunoResearch Laboratories) was diluted to 1:250 and supplemented with DAPI (Invitrogen) diluted 1:2,000 for 1 h at RT. The binding activity of antibodies to the DENV-2-infected or transfected cells were observed and photographed through a fluorescence microscope.