Fig. 4

Non-classical monocytes are the major in vivo cellular target of ZIKV infection. a, b ZIKV-infected cells isolated from blood or c, d PLN in the males were identified by flow cytometry following intracellular staining for ZIKV-NS3 and cell surface staining to identify immune cell subsets (n = 4/timepoint). Positive cells were identified after background subtraction and adjusting for autofluorescence. The threshold limit was ≥100 cells/gate, and cell types that did not reach this threshold for all animals at all timepoints are excluded. a, c Percentages of NS3⁺ cells within myeloid DCs (mDCs), non-classical monocytes (Non-Class. Mon.), classical monocytes (Class. Mon.), NK cells, neutrophils (Neutr.), B cells, or T cells are shown 1, 2, and 3 dpi in blood and 7 and 14 dpi in the PLN. Dots are individual animals (males) with box plots showing the median with interquartile ranges. b Scatter plot and Spearman's correlation analysis of early (1–3 dpi) plasma viremia and frequencies of mDCs and non-classical monocytes in the blood at matched timepoints (1–3 dpi). d Correlation between viral load in the PLN and frequencies of mDCs and non-classical monocytes in the PLN at matched timepoints (7–21 dpi). Dotted line indicates the limit of viral RNA detection (25 copies per mg). b, d Spearman’s rank correlation coefficients are shown; significance of the unadjusted p-values are indicated as follows: **p ≤ 0.01