Streptococcus equi IgG-cleaving protease IdeE (IdeE)

Streptococcus equi IgG-cleaving protease IdeE (also known as IgdE equi) is a secreted cysteine protease produced by Streptococcus equi subsp. equi, a pathogen causing strangles in horses.[1][5] It specifically cleaves equine IgG7 in the hinge region, generating a characteristic 32 kDa fragment and impairing IgG effector functions such as complement activation, opsonization, and phagocytosis, thereby promoting bacterial immune evasion.[1][5] IdeE is distinct from other S. equi proteases like IdeZ and IdeZ2, which have broader IgG specificity across host species, while IdeE shows high subtype selectivity for equine IgG7 due to recognition of specific hinge sequences adjacent to a CPxCP motif.[1] This protease homolog shares structural and functional similarities with IdeS from S. pyogenes, acting as an endopeptidase that targets the heavy chain without cleaving synthetic peptides or non-equine IgGs.[1][3][5] In bacterial pathogenesis, IdeE contributes to S. equi's survival by neutralizing host antibody responses during infection.[1][5] No therapeutic drugs targeting IdeE are reported, reflecting its role as a microbial virulence factor rather than a human therapeutic target.[1][2][5]

Other names

IgdE equiIgG-degrading enzyme of Streptococcus equi subsp. equi