Figure 8.

Strain-dependent differences during NTHi persistence. (A) The diversity of seven clinical NTHi isolates were assessed by ParSNP using default parameters and NTHi 86-028NP as the reference strain. Strains were isolated from either from sputum sample (green), nasal brushing (orange) or protected bronchial brushes of the lung (blue). Phylogenetic tree was created in FigTree using ParSNP output files and strains highlighted in red (ST14, ST408 and ST201) indicate the strains chosen for further in vitro experimental analysis. (B) Invasion and persistence within MDM by the three chosen different strains of NTHi was measured by live viable counting at the 6 h and 24 h time points. (C) Expression of the top regulated NTHi genes were differentially expressed by additional clinical strains of NTHi during intracellular persistence. Gene expression was normalised to NTHi rho gene and data are shown as fold change in expression from 6 h to 24 h Graphs show paired data and lines indicate medians. N = 6. Data were analysed using Friedman test with Dunn’s multiple comparisons; *p < 0.05, **p < 0.01.