FIG 4 .

Recombinant M. catarrhalis UspA2 and UspA2H bind to fibrillar collagens I and II. (A and B) Binding of recombinant ¹²⁵I-labeled UspA1, UspA2, and UspA2H to collagen I (A) or collagen II (B). ¹²⁵I-labeled UspA2 and UspA2H (28 to 156 kcpm added) showed significantly higher levels of binding to collagens I and II than did UspA1 (P value range, 0.01 to 0.001). Mean values from three independent experiments in triplicates are shown. Error bars indicate standard deviations. Multiple comparisons were performed using two-way ANOVA. (C and D) TEM images showing binding of gold-labeled UspA1, UspA2, and UspA2H to a grid coated with collagen I (C) or collagen II (D). The gold particles, appearing as black dots and indicated by arrows, show UspA2 and UspA2H bound to collagen fibrils.