Fig. 1.

Abrogation of ospAB results in constitutive activation of ospC. Wild-type infectious clone BbAH130 of B. burgdorferi strain 297 (wt) and the isogenic ospAB mutant (ΔospAB) were cultivated in BSK-H medium (pH 7.5) at 23°C (23), 37°C (37) or 37°C with media adjusted to pH 8.0 (37/pH 8). Spirochaetes were harvested at a cell density of 5 × 10⁷ ml⁻¹ and cell lysates were subjected to SDS-PAGE and proteins stained with Coomassie blue. Each gel lane was loaded with lysates of approximately 5 × 10⁷ spirochaetes. Numbers at the left of the figure denote molecular mass markers in kilodaltons. The bands corresponding OspA and OspC were labelled on the right.