Fig. 3.

NS1-specific antibodies do not cause antibody-dependent enhancement (ADE) of infection in vitro. To examine whether enhancement of flavivirus infection in vitro is observed, ZIKV NS1-specific mAbs or pooled serum from a DENV positive donor were incubated with a PRVABC59 or b DENV-3 viruses and added to FcγR bearing K562 cells. All mAbs were tested at a starting concentration of 100 ng per mL and were serially diluted four-fold. DENV positive control sera was diluted five-fold initially and serially diluted four-fold. The assay was run in duplicate and fold induction was measured as number of infected cells as measured by flow cytometry divided by infected cells with no antibody or serum added. Sera were obtained through a screening of blood donations in Puerto Rico as described previously in Bardina et al.¹⁴. Plotted values represent mean value and standard deviation