Figure 2. Native protein expression stimulated by the in vitro conditions mimicking those of the mammalian host.

The expression levels of LigA were evaluated by ELISA, following exposure to the various conditions and combinations: TS – Temperature upshift from 30°C to 37°C, PO – Physiological osmolarity, Sp – Spermine induction, pH – Urine pH induction. (A) Temperature upshift and physiological osmolarity. (B) Temperature upshift, physiological osmolarity and spermine (intracellular level). (C) Temperature upshift, physiological osmolarity and pH reduction from 7.2 to 6.7. A non-induced L. interrogans serovar Copenhageni str. Fiocruz L1-130 (NI-24) was cultivated in vitro for 24 h under standard conditions as a control. Protein expression was measured at one, 12 and 24 h post-induction and the results are expressed as mean optical density ± standard error (bars). The assay was standardized according to an OD₄₂₀ of 0.25. Data from two independent and significant experiments are shown.