Features of Two New Proteins with OmpA-like domains Identified in the genome sequences of Leptospira interrogans

ABSTRACT

Leptospirosis is an acute febrile disease caused by pathogenic spirochetes of the genus Leptospira. It is considered an important re-emerging infectious disease that affects humans worldwide. The knowledge about the mechanisms by which pathogenic leptospires invadeand colonize the host remains limited since very few virulence factors contributing to the pathogenesis of the disease have been identified. Here, we report the identification and characterization of two new leptospiral proteins with OmpA-like domains. The recombinant proteins,which exhibit extracellular matrix-binding properties, are called Lsa46 - LIC13479 andLsa77 - LIC10050 (Leptospiral surface adhesins of 46 and 77 kDa, respectively). Attachmentof Lsa46 and Lsa77 to laminin was specific, dose dependent and saturable, with KD valuesof 24.3 ± 17.0 and 53.0 ± 17.5 nM, respectively. Lsa46 and Lsa77 also bind plasma fibronectin,and both adhesins are plasminogen (PLG)-interacting proteins, capable of generatingplasmin (PLA) and as such, increase the proteolytic ability of leptospires. The proteins corresponding to Lsa46 and Lsa77 are present in virulent L. interrogans L1-130 and in saprophyteL. biflexa Patoc 1 strains, as detected by immunofluorescence. The adhesins are recognizedby human leptospiros is serum samples at the on set and convalescent phases of the disease, suggesting that they are expressed during infection. Taken together, our data could offer valuable information to the understanding of leptospiral pathogenesis...