Identification of the hemolysis-associated protein 1 as a cross-protectiveimmunogen of Leptospira interrogans by adenovirus-mediated vaccination

New vaccine strategies are needed for the prevention of leptospirosis, a wi despread human and animal disease caused by pathogenic leptospires. Our pre vious work determined that a protein leptospiral extract conferred cross-pr otection in a gerbil model of leptospirosis. The 31- to 34-kDa protein frac tion of Leptospira interrogans serovar autumnalis was shown sufficient for this purpose. In the present study, N-terminal sequencing of a 32-kDa fract ion and Southern blotting of genomic DNA with corresponding degenerated oli gonucleotide probes identified two of its constituents: hemolysis-associate d protein 1 (Hap1) and the outer membrane Leptospira protein 1 (OmpL1). Ade novirus-mediated Hap1 vaccination induces significant protection against a virulent heterologous Leptospira challenge in gerbils, whereas a similar Om pL1 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.