Epitope mapping of pathogenic Leptospira LipL32

Aims: To identify LipL32 epitopes and to evaluate their capability to recognize specific antibodies using ELISA. Methods and Results: Epitope mapping by means of a library of overlapping peptide fragments prepared by simultaneous and parallel solid phase peptide synthesis on derivatized cellulose membranes (SPOT synthesis) was carried out. Eighty-seven overlapping decapentapeptides corresponding to the complete sequence of LipL32 were synthesized. According to spot-image intensities, the most reactive sequences were localized in regions 151-177 (sequence AAKAKPVQKLDDDDDGDDTYKEERHNK) and 181-204 (sequence LTRIKIPNPPKSFDDLKNIDTKKL). Two peptides (P1 and P2) corresponding to these sequences were synthesized, and their reactivity evaluated using ELISA test. Conclusions: Epitope identification and analysis suggested the existence of two antigenic regions within LipL32. These LipL32 reactive regions were highly conserved among antigenically variants of Leptospira spp. isolates. Peptides containing these regions (P1 and P2) showed a good capability for anti-leptospiral antibody recognition. Significance and Impact of the Study: This finding could have potential relevance not only for serodiagnosis but also as a starting point for the characterization of targets for vaccine design.