Domains Eap3 and Eap4 are sufficient to inhibit the lectin pathway of complement. Lectin pathway complement activity was assessed over a logarithmic dilution series of various Eap proteins. 1% (v/v) pooled human serum was used as a source of complement components, and each assay point was repeated in triplicate prior to fitting each series to a dose‐response curve. Legends are inset. (A) Lectin pathway activity in the presence full‐length Eap, Eap12, Eap23, or Eap34 was assessed by ELISA specific for either C3b (top panel) or C5b‐9 (bottom panel). (B) Lectin pathway activity in the presence of Eap1, Eap2, Eap3, or Eap4 was assessed by ELISA specific for either C3b (top panel) or C5b‐9 (bottom panel).