Figure 1. Far-Western analysis showing interaction of C1inh from normal human serum with an unknown B. pertussis factor migrating at ca. 90 to 100 kDa.

B. pertussis strain BP338 (wild type) and its isogenic mutant BP347 (bvgS::Tn5) were grown without (−) or with (+) Bvg-modulating agent MgSO₄ (50 mM) prior to performing the Far-Western assay using normal human serum as the probe, followed by detection using anti-C1inh antibody.