CONICET | Buscador de Institutos y Recursos Humanos

Leptospirosis is a zoonotic disease of global distribution, which affects both animals and men. Pathogenic leptospires, the bacteria that cause this disease, require iron for their growth, and these spirochetes probably use their hemolysins, such as the sphingomyelinases, as a way to obtain this important nutrient from host red blood cells during infection. We have expressed and purified the leptospiral sphingomyelinases Sph1, Sph2, Sph4 and SphH in a heterologous system. However, the recombinant proteins were not able to hemolyse sheep erythrocytes, despite having regular secondary structures. Transcripts for all sphingomyelinases tested were detected by RT-PCR analyses, but only Sph2 and SphH native proteins could be detected in Western blot assays using Leptospira whole extracts as well as in renal tubules of infected hamsters, as demonstrated by immunohistochemistry. Moreover, antibodies present in the serum of a human patient with laboratory-confirmed leptospirosis recognized Sph2, indicating that this sphingomyelinase is expressed and exposed to the immune system during infection in humans. However, in an animal challenge model, none of the sphingomyelinases tested conferred protection against leptospirosis.