The identification of MacSe in Streptococcus equi ssp. equi

Abstract

Streptococcus equi subsp. equi (S. equi ssp. equi) causes equine strangles, a highly contagious and widespread purulent lymphadenitis of the head and neck. We have identified MacSe, a novel protein of S. equi, by screening a phage library of 3-8 kb random DNA fragments of S. equi CF32. MacSe shares 62% and 67.5% amino acid homology with Mac5005 and Mac8345 of S. pyogenes respectively. Expression during infection was shown by strong reactivity of the protein with convalescent sera and mucosal wash IgA of ponies infected by commingling exposure. Release into the culture medium was detected during the log phase of growth. Dose dependent anti-phagocytic activity for equine neutrophils involved interaction of MacSe with C3 and neutrophils.