Western blot analysis of ErpA/I/N, BppA, BppB, and BppC expression by B. burgdorferi. Left column, bacteria cultured at 23°C or shifted from 23 to 35°C. Middle column, bacteria cultured at pH 7.0 or 8.0. Right column, bacteria treated with MNNG (+) or left untreated (−). nd, not done.