Fig. 3

RSV disease, viral load, and CXCL8 levels in healthy and RSV-infected individuals can be explained by nasopharyngeal microbial makeup (genus-level). Redundancy analysis (RDA) biplots are shown. Nasopharyngeal genus-level microbiota from healthy and RSV-infected individuals are significantly different, irrespective of disease severity (a) (according to a permutation test; p value = 0.001). Triangles are the centroids of the study sample groups: RSV (red) and healthy control (green). RDA of RSV-infected individuals (healthy and recovery samples were excluded from analysis) shows that nasopharyngeal genus-level microbiota can significantly be separated based on viral load (b) (Ct threshold plotted: higher Ct number corresponds to higher number of PCR cycles before confident virus detection, hence lower viral load; p value = 0.036). For a and b, the blue arrows are the 10 best-fitting genera (names in italic), which are the genera best explaining microbiota compositional differences between disease status (a) or different levels of RSV virus (b) as plotted on the horizontal axis. RDA of healthy and RSV-infected individuals shows that nasopharyngeal genus-level microbiota can significantly be separated based on levels of CXCL8 (c) (p value = 0.036; log transformation was set to 1000). The first component (horizontal axis) is optimized to explain CXCL8 level based on microbiota relative abundances (concentration of CXCL8 in pg/μl). Correspondingly, the blue arrows are the genera (names in italic) explaining at least 5% of this variation. RDA was corrected for age, gender, and birth weight. See Additional file 2: Figure S2 for similar analysis on the OTU level