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. 2026 Jan 23;16:1724684. doi: 10.3389/fimmu.2025.1724684

Figure 2.

Diagram with four panels A, B, C, and D. Panel A shows the experimental process of bone marrow cells developing into osteoclasts, infected with *Coxiella burnetii*. Panel B displays fluorescent microscopy images of wild type (WT) and ΔdotA strains at 24 and 72 hours post-infection, highlighting actin, DNA, and *Coxiella*. Panels C and D are bar graphs comparing *Coxiella* burden in osteoclast and non-osteoclast cells at different times with statistical significance indicated.

C. burnetii needs dotA to sustain its growth in myeloid cells including osteoclasts. (A) Osteoclasts were differentiated from bone marrow progenitor cells in presence of M-CSF and RANKL. Cells were then infected after 2 days of differentiation with C. burnetii WT or ΔdotA at MOI 10. Uninfected osteclasts (n.i.) were used as control. (B) Osteoclasts differentiated from bone marrow progenitor cells were infected after 2 days of differentiation with C. burnetii WT or ΔdotA at MOI 10. After 24 or 72 hpi, cells were stained for Coxiella (green - Alexa488), actin (red – Alexa647) and DNA (blue - DAPI) and imaged by fluorescent CLSFM (n=3). The bacterial burden was quantified using ImageJ to calculate a ratio of the measured intensity of the staining emitted by C. burnetii within each cell divided by the measured surface of this cell. The scale bar represents 20 µm. The bacterial burden was analyzed for the osteoclasts (C) and for the other myeloid cells (D). Data are shown as mean ± SD. Circle represent individual cells.