FIG. 3.

Kinetics experiment for uspA1 transcription and UspA1 surface expression. M. catarrhalis O35E cells were grown to mid-logarithmic phase at 37°C. The culture was then split into two portions, which were incubated further at 37°C and 26°C, respectively. Transcription of uspA1 and quantity of UspA1 on the bacterial surface were assessed in parallel at different time points. Transcription quantified by real-time RT-PCR (gray bars) is illustrated as up-regulation at 26°C (n-fold) in comparison with that at 37°C (primary y axis). Protein expression was analyzed by FACS using the UspA1-specific antibody mAb24B5 and is presented as mean fluorescence values (secondary y axis) for bacterial populations incubated at 26°C (filled symbols) and 37°C (open symbols). M1 (filled squares, open diamonds) and M2 (filled triangles, open circles) are populations expressing different levels of UspA1. Strain O35E.1, which lacks expression of UspA1, was included as a negative control (not shown).