A single residue change in Vibrio harveyi hemolysin results in the loss of phospholipase and hemolytic activities and pathogenicity for turbot (Scophthalmus maximus)

Vibrio harveyi hemolysin, an important virulence determinant in fish pathogenesis, was further characterized, and the enzyme was identified as a phospholipase B by gas chromatography. Site-directed mutagenesis revealed that a specific residue, Ser153, was critical for its enzymatic activity and for its virulence in fish.