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Title: Studies on the hemin-binding protein HbpA and the iron-regulated virulence factor sphingomyelinase in pathogenic leptospires
Researcher: Velineni, Sridhar
Guide(s): Sritharan, Manjula
Keywords: Animal Science
pathogenic leptospires
Upload Date: 14-Aug-2012
University: University of Hyderabad
Completed Date: March 2009
Abstract: Leptospirosis is a spirochetal zoonosis of worldwide distribution. It is caused by the pathogenic members of the genus Leptospira that includes more than 250 different serovars, whose distribution may be restricted geographically. Despite the high antigenicity of surface lipopolysaccharide molecules, they afford little cross-protection against infectivity by other serovars. In addition, an economic and easy-to do specific diagnostic test is necessary for early diagnosis. Thus candidate antigens are to be identified both for diagnosis and vaccine purposes. This can be achieved by a better understanding of host-pathogen interactions. Acquisition of iron is one of the important factors contributing to the successful establishment of the pathogen, as the amount of available iron is limiting in the mammalian host. Though the requirement of iron byLeptospira sp. is known, there are no reports on the mechanism of iron acquisition. Earlier studies in our lab showed for the first time that pathogenic leptospires acquire iron directly via a hemin receptor. Siderophores could not be detected in the spent growth medium. Using a bioinformatics approach, a TonB-dependent outer membrane protein (LB191) was identified in Leptospira interrogans serovar Lai using the Fe3+-enterochelin receptor FepA of Escherichia coli. The protein, referred to as HbpA showed a similar fold as other Fe3+-siderophore receptors upon homology modeling. Wet lab experiments with recombinant HbpA confirmed it to be a hemin receptor. In this study, after several trials with different chelators, we established conditions of iron-deprivation for the growth of Leptospira spp. with EDDA at 200 µM final concentration, with a final incubation at 37ºC for 5½ h. We detected HbpA as an 81 kDa protein in low-iron organisms of L. interrogans serovar Lai that was not expressed in high-iron conditions. Analysis of several leptospiral species showed that HbpA was restricted to serovars belonging to L. interrogans. Immunofluorescence studies using anti-HbpA antibodies..
Pagination: 154p.
Appears in Departments:School of life Sciences

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02_declaration.pdf25.56 kBAdobe PDFView/Open
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04_acknowledgements.pdf25.56 kBAdobe PDFView/Open
05_contents.pdf33.81 kBAdobe PDFView/Open
06_list of figures.pdf27.21 kBAdobe PDFView/Open
07_abbreviations.pdf21.07 kBAdobe PDFView/Open
08_abstract.pdf25.69 kBAdobe PDFView/Open
09_chapter 1.pdf1.74 MBAdobe PDFView/Open
10_chapter 2.pdf220.86 kBAdobe PDFView/Open
11_chapter 3.pdf1.21 MBAdobe PDFView/Open
12_chapter 4.pdf387.07 kBAdobe PDFView/Open
13_chapter 5.pdf26.25 kBAdobe PDFView/Open
14_chapter 6.pdf208.93 kBAdobe PDFView/Open
15_publications.pdf25.2 kBAdobe PDFView/Open

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