Discovery of Leptospira spp. seroreactive peptides using ORFeome phage display.
Leptospirosis is an infectious disease that is transmitted from animals to humans. It is associated with a broad range of clinical presentations, and diagnostic tests with high diagnostic accuracy are required in order to enable accurate diagnosis. Leptospirosis is diagnosed by detecting DNA of the pathogen or antibodies against it in patients’ blood; the latter are preferred in resource limited regions, and diagnostics based on peptides (small fragments of proteins) are advantageous because they are inexpensive to produce and more stable in hot climates than full-length proteins. We used a technique called open reading frame phage display to identify peptides from Leptospira spp. that could be used to detect antibodies against them in human blood. In this method, the pathogen’s genome is fragmented, the corresponding peptides displayed on the surfaces of phages (viruses that infect bacteria), and the peptides that bind most strongly to the patients’ antibodies are then selected by screening. Using this method, we identified 2 leptospiral peptides that accurately identified antibodies against Leptospira spp. in sera from patients with leptospirosis. These results are encouraging because they demonstrate that ORFeome phage display may be a powerful tool to develop better diagnostics for leptospirosis for use in less developed areas.