A low passage, infectious, and serum resistant B.
burgdorferi strain B31-5A4 (“B31-5A4”) or a high
passage, non-infectious, and serum sensitive B. burgdorferi
strain B313 (“B313”) was incubated for 4h with indicated
concentrations of OmCI as well as (A, C, and E) human or (B,
D, and F) quail serum with a final concentration of 40 %.
Heat-inactivated human or quail serum was included as controls. The number of
motile spirochetes was then assessed microscopically. The percentage of survival
for those B. burgdorferi strains was calculated using the
number of mobile spirochetes at 4 h post incubation normalized to that prior to
the incubation with serum. The work was performed on three independent
experiments; within each experiment, samples were run in triplicate. The result
shown here is the experiment (A and B) 1, (C and D) 2,
and (E and F) 3 from the average survival percentage ±
standard deviation of three replicates in each experiment. The concentration of
OmCI to inhibit 50 % levels of serum killing (IC50) was obtained by
fitting the data points using nonlinear regression methods (IC50 =
3.78 ± 1.71 μM for human serum, IC50 = 2.94 ±
0.83 μM for quail serum).