The complement system contributes significantly to antibody‐mediated killing of B. hermsii in vitro.
B. hermsii were incubated in 50% freshly isolated UI, HI‐UI, PC, or HI‐PC mouse sera. BSK‐II culture medium alone served as the negative control. Samples were incubated at 37°C, and numbers of motile and intact spirochetes were counted after 2 or 24 h. There were no significant differences in IgM titers after HI of the sera samples (data not shown). (A) Motile spirochetes, as percent of intact bacteria, after 2 h incubation. (B) Number of intact spirochetes after 2 h, relative to the number of intact bacteria in the control BSK‐II wells. (C) Motile spirochetes, as percent of intact bacteria, after 24 h incubation. (D) Number of intact spirochetes after 24 h, relative to the number of intact bacteria in the control BSK‐II wells. Error bars indicate 1 sd from the mean. *, Results statistically significant from BSK‐II control (P<0.05).