New vaccine strategies are needed for the prevention of leptospirosis, a widespread human and animal disease caused by pathogenic leptospires. Our previous work determined that a protein leptospiral extract conferred cross-protection in a gerbil model of leptospirosis. The 31-to 34-kDa protein fraction of Leptospira interrogans serovar autumnalis was shown sufficient for this purpose. In the present study, N-terminal sequencing of a 32-kDa fraction and Southern blotting of genomic DNA with corresponding degenerated oligonucleotide probes identified two of its constituents: hemolysis-associated protein 1 (Hap1) and the outer membrane Leptospira protein 1 (OmpL1). Adenovirus-mediated Hap1 vaccination induces significant protection against a virulent heterologous Leptospira challenge in gerbils, whereas a similar OmpL1 construct failed to protect the animals. These data indicate that Hap1 could be a good candidate for developing a new generation of vaccines able to induce broad protection against leptospirosis disease.

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The coypu (Myocastor coypus), a rodent whose natural habitat is stagnant freshwater, has become a widespread pest in France within the last decade. This study investigated the prevalence of seropositivity and the renal carriage of leptospires in coypus in order to evaluate their role in terms of the risk of infection by Leptospira interrogans in domestic animals and humans. The study involved the application of serological and bacteriological methods to identify leptospires infection and/or carriage in 738 coypus trapped from 1996 to 1999 in six areas of France. Seroprevalence in samples ranged from 16.5 to 66%, and three field strains were isolated (two L. interrogans Icterohaemorrhagiae and one L. interrogans Sejroe). This first report on the isolation of leptospires from coypus in France emphasises the role of this animal in the epidemiology of leptospirosis.