RESUMEN
Leptospirosis is a zoonotic infectious disease that affects both humans and animals. The existing genetic toolsfor Leptospira spp. have improved our understanding of the biology of this spirochete as well as the interaction ofpathogenic leptospires with the mammalian host. However, new tools are necessary to provide novel and useful information to the field. A series of promoter-probe vectors carrying a reporter gene encoding greenfluorescent protein (GFP) were constructed for use in L. biflexa. They were tested by constructing transcriptional fusions between the lipL41, Leptospiral Immunoglobulin-like A (ligA) and Sphingomielynase 2 (sph2) promoters from L. interrogansand the reporter gene. ligA and sph2 promoters were the most active, in comparison to the lipL41 promoter and the noninduced controls. The results obtained are in agreement with LigA expression from the L. interrogans Fiocruz L1-130 strain. The novel vectors facilitated the in vitro evaluation of L. interrogans promoter activity under defined growth conditions which simulate the mammalian host environment. The fluorescence and rt-PCR data obtained closely reflectedtranscriptional regulation of the promoters, thus demonstrating the suitability of these vectors for assessing promoter activity in L. biflexa.