FIG. 1.

Serum susceptibility among borrelial isolates. Growth inhibition assays of susceptibility to human serum of B. spielmanii TIsar2 and TIsar3, as well as control strains B. burgdorferi LW2 and B. garinii G1 (27). Spirochetes were incubated in either 50% NHS (filled triangles) or 50% heat-inactivated NHS (open triangles) over a cultivation period of 10 days at 33°C. Color changes were monitored by measurement of the absorbance at 562/630 nm. All experiments were performed three times in which each test was done five times with very similar results. For clarity only data from representative experiments are shown. Error bars represent ± standard deviations (SDs). d, day.