May be involved in virulence. Binds human plasminogen (PLG) and stimulates its proteolytic cleavage to enzymatically active plasmin in the presence of an urokinase-type PLG activator in vitro. Activated plasmin has proteolytic activity which may help the bacteria to spread throughout the host by degrading extracellular matrix components, facilitating tissue penetration and invasion. May be useful for detecting a broad spectrum of Leptospira infection in humans and animals due to its presence in several pathogenic serovars of L.interrogans including copenhageni, canicola, hardjo, icterohaemorrhagiae and pomona, and also in L.borgpetersenii hardjo. May be used for serodiagnosis of both early and convalescent phases of leptospirosis infectious disease.