Thesis (M.Sc.)--Chulalongkorn University, 2011

Leptospirosis is caused by Leptospira interrogans. Leptospirosis is a systemic disease in humans that manifests a broad spectrum of clinical signs. However, pathogenesis of leptospirosis remains unclear. Most pathogenic bacteria express surface-associated proteins to promote the interaction with host cell receptors. Loa22 is a highly conserved OMP among pathogenic leptospires. Moreover, this protein was up-regulated during host infection. To identify host surface proteins that interact with Loa22, the phage display technology was utilized in this study. T7 cDNA liver phage display library was used for biopanning against 1) whole-cell, wild-type Leptospira and subsequent subtraction with loa22- mutant; and 2) recombinant Loa22. Affinity-selected plaques from the final round of panning were selected for sequencing. The results showed that phages displaying 4 sequence patterns were enriched when rLoa22 was used as a target. The major peptide sequence of selected phages against rLoa22 matched fibrinogen. In addition, this protein demonstrated specific binding ability to rLoa22 in a dose-dependent manner. However, the interaction of Loa22 and fibrinogen in vivo requires further investigations.