Sap2 is a type of aspartate protease that has been reported to cleave various components of the complement system, including C3b, C4, C5, and factor H, at pH 5, indicating its potential non‐specificity.[9c] Our in vivo findings showed that infection with the site‐directed mutated Sap2‐273L strain in mice led to reduced release of C3a and deposition of C3b/iC3b. Here, C4A is linked to infection.