Enhanced DENV uptake by K562 cells in the presence of HMAbs. Human K562 cells were infected with DENV-1 in the presence of increasing concentrations of the antibodies. RNA was extracted from cell lysates and quantitative RT-PCR was performed with a DENV-1 specific primer pair specific for the NS1 region as a measure of infectious equivalents. A HMAb 2.3D. B 3.6D. C 4.8A.