FIG 1 .

CspA inhibits the alternative pathway of complement independent of factor H. (A) CspA and ErpP, but not CspZ, ErpC, or ErpA, inhibit alternative pathway-mediated hemolysis. The five recombinant borrelial proteins (5 to 50 µg/ml) were added to NHS, and then the mixture was applied to rabbit erythrocytes. Following incubation, erythrocyte lysis was recorded. (B) CspA inhibited alternative pathway-mediated hemolysis in 2.5 to 10% serum. The CspA (10 µg/ml) inhibitory effect on alternative pathway-mediated hemolysis of rabbit erythrocytes using NHS at concentrations ranging from 2.5 to 10% was analyzed. (C) CspA inhibited alternative pathway-mediated hemolysis in complement-active human serum depleted for factor H (HSΔFactor H). CspA (50 µg/ml) was added to HSΔFactor H (15%), and then the mixture was applied to sheep erythrocytes. (D) Lysis of rabbit erythrocytes in serum derived from the indicated species, i.e., mouse, sheep, goat, guinea pig, or dog. Each panel represents the mean values from three separate experiments, and error bars show standard deviations (SD). *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001.