FIG. 4.

An isogenic mutant strain of NTHI lacking P5 adheres poorly to CHO-ICAM-1 cells compared to its P5-sufficient parental strain. CHO-ICAM-1 cells were incubated with NTHI strains and their isogenic mutants lacking HMW1 and HMW2 (strain 12, HMW⁻); HMW1, HMW2, and Hap proteins (strain N187, HMW⁻, and N187, Hap⁻); P2 fimbriae (strain Rd, P2⁻); and P5 fimbriae (strain 1128f⁻) and expressing LOS (strain 2019) or truncated LOS (strain 2019, pgmB::erm), and adherent bacteria were quantified. Only the P5 fimbria-deficient strain 1128f⁻ had significant reduction in adhesion to CHO-ICAM-1 cells compared to its parental strain (*, P = 0.003). The data represent the mean ± standard error of five independent experiments.