Fig. 3. Electrostatic potential surface of various OspCs. Electrostatic potential surface of (A) HB19 and (B) 212 as viewed from the top of the molecule (orthogonal to the view in Figure 1A). 212 was modeled based on HB19 coordinates. The electrostatic potential surface of B31 (not shown) is similar to that of HB19. The negative and positive potentials are shown in red and blue. The HB19 and B31 spirochetes are classified as being invasive while the 212 spirochete is from non-invasive groups. The electrostatic surface potential at the top of the OspC dimers from spirochetes in invasive groups is highly negative and clearly different from those of the non-invasive groups.