As a representative result shown in Fig 3A using a DENV-1 immune serum sample (D1-E01), among major cell types of interest, we observed significant elevated ZIKV infection in monocytes (CD14+CD3-CD19-) over a range of serum dilutions (1/20-1/12,500), with the peak enhancement (0.30% infection) at the dilution rate of 1/2,500 compared to the percentage of ZIKV infected cells without serum treatment (0.040% infection). Here, CD19 is linked to infection.