FIG. 2.

Binding of purified FH, C4BP, and BSA to B. recurrentis (strains A5 and A17) and B. duttonii (strains La and Ku) (A) and of FH and C4BP to B. duttonii (KU) and B. burgdorferi sensu stricto (IA) (B). The spirochetes were incubated with ¹²⁵I-labeled FH, C4BP, or BSA (approximately 50,000 cpm each) for 30 min, and unbound protein was separated from borrelia-bound protein by centrifugation through 20% sucrose columns. The background was detected as sedimentation of the radioactivity in the absence of any bacteria (1 to 3%) and was subtracted from the raw data, resulting in the values shown. Means ± standard deviations of quadruplicate assays are shown.