Fig. 1: Influenza A virus infection increases DCC in lungs.
From: Respiratory viral infections awaken metastatic breast cancer cells in lungs
a, MMTV-Her2 female mice in an FVB background were infected with a sublethal dose of Puerto Rico A/PR/8/34 H1N1 IAV by intranasal administration. Lungs and mammary glands were taken for analysis at the time points indicated after infection. b,c, Immunofluorescence (b) and quantification of HER2+ cells in lungs (c) at 3, 6, 9, 15, 28 and 60 dpi. The total number of HER2+ cells from three sections of the whole lung were quantified (n = 4 per group, n = 3 at 15 dpi). Lung sections were stained with DAPI (blue) and HER2 (green) as a marker for DCCs (b). d, Immunofluorescence and quantification of HER2+ cells in lungs 9 months after an influenza infection (n = 3 PBS, n = 5 IAV). e, Quantification of HER2+ cells in C57BL6/J MMTV-Her2 mouse lungs at 15 dpi with IAV (n = 4 PBS, n = 3 IAV). f, Immunohistochemistry and quantification of PyMT+ micrometastases defined by lesions with an area of less than 0.03 mm2 (n = 7 per group). g, EO771 mammary tumour cells were implanted into the mammary fat pads of C57BL/6 mice (n = 4 per group) and infected with IAV or PBS control after 31 days (experiment 1) and 20 days (experiment 2). The mice were implanted with 2 × 105 (experiment 1) or 1 × 106 EO771 (experiment 2) cells across two experiments, and combined results are shown. Lungs were taken for analysis 18 days (experiment 1) and 17 days (experiment 2) after infection and stained with H&E, and the tumour area and the numbers of lesions were quantified. For each experiment, the average of the quantification of the PBS-treated mouse lungs was set to 1, so that a fold change could be calculated. Significance was determined by one-way analysis of variance (ANOVA). All box-and-whisker plots are presented as maximum value (top line), median value (middle line) and minimum value (bottom line), with all data points shown as dots. Scale bars: a and d, 25 μm; f, 200 μm; g, 1 mm. Illustration in a created using BioRender (De Dominici, M., https://BioRender.com/i40c047; 2025). All replicates are biological.
