Introduction and Objectives: In recent years there have been major advances in the understanding of leptospiral biology and the molecular basis of pathogenesis, yet the protein LipL32 remains an enigma of leptospiral biology. LipL32 (also known as Hap1) is an outer membrane, surface exposed lipoprotein and is the most abundant protein in the cell. LipL32 is found exclusively in pathogenic leptospires, is highly conserved, expressed in vivo and is highly immunogenic. Materials and Methods: In an attempt to enhance the immune response, LipL32 coupled to or co-administered with the B subunit of the Escherichia coli heat-labile enterotoxin (LTB) in a hamster model of leptospirosis. After homologous challenge with 5× the 50% lethal dose (LD (50)) of Leptospira interrogans, animals vaccinated with LipL32 co-administered with LTB and LTB. Another study provides evidence that LipL32 is involved in the protective response against L. interrogans serovar Canicola in hamsters and is the first reported link to LipL32-induced protection against kidney invasion. Results: It has been shown that LipL32 had significantly higher survival rates (P < 0.05) than animals from the control group. This is the first report of a protective immune response afforded by a subunit vaccine using LipL32 and represents an important contribution toward the development of improved leptospirosis vaccines. Also it is the first reported link to LipL32-induced protection against kidney invasion. Conclusions: It has been shown that vaccination with LipL32 protein alone could provide a protective response against challenge with L. interrogans serovar Canicola to hamsters.

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