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Diagnostic potential of an iron-regulated hemin-binding protein HbpA that is widely conserved in Leptospira
Velineni Sridhar1, Sundru Manjulata Devi, Niyaz Ahmed
1School of Life Sciences, University of Hyderabad, Hyderabad, India.
Abstract:
Like most bacteria, Leptospira spp. requires iron for growth. However, they face conditions of iron limitation due to the low solubility of the ferric iron and additionally due to the observation that most of the available iron is held as protein-bound iron by the mammalian host. Our experimental observations with pathogenic Leptospira showed that they do not elaborate siderophores upon iron limitation. In Leptospira interrogans serovar Lai, we demonstrated direct acquisition of iron via an iron-regulated hemin-binding protein HbpA. PCR analysis and Southern hybridization studies revealed that the hbpA gene was conserved in the serovars belonging to L. interrogans species and was absent in the non-pathogenic Leptospira biflexa serovar Patoc and Leptospira meyeri serovar Ranarum. Here, we extended the PCR-based detection of the hbpA gene to clinical isolates and demonstrated the hbpA amplicon in all the serovars belonging to L. interrogans species from a total collection of 91 clinical isolates obtained from different geographical regions. In addition, we detected anti-HbpA antibodies in the serum of patients with leptospirosis. PCR-based detection of hbpA in clinical isolates of serovars and the in vivo expression of HbpA reflects the diagnostic potential of this antigen.
Insights
Pathogenic Leptospira species acquire iron using a hemin-binding protein (HbpA), a gene conserved in pathogenic strains but absent in non-pathogenic ones. This finding highlights HbpA
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Iron Metabolism
Background:
- Leptospira spp. require iron for growth, but face scarcity in mammalian hosts due to low ferric iron solubility and host iron sequestration.
- Pathogenic Leptospira do not produce siderophores to scavenge iron under limited conditions.
- Iron acquisition mechanisms are crucial for bacterial survival and pathogenesis.
Purpose of the Study:
- To investigate the iron acquisition mechanisms in pathogenic Leptospira.
- To identify and characterize the role of specific iron-binding proteins.
- To assess the diagnostic potential of identified iron-related genes and proteins in leptospirosis.
Main Methods:
- Experimental observations on iron-limited pathogenic Leptospira.
- Demonstration of direct iron acquisition via hemin-binding protein A (HbpA) in Leptospira interrogans serovar Lai.
- Polymerase Chain Reaction (PCR) and Southern hybridization to detect the hbpA gene.
- Detection of anti-HbpA antibodies in human serum samples.
Main Results:
- Leptospira interrogans serovar Lai directly acquires iron through the iron-regulated hemin-binding protein HbpA.
- The hbpA gene is conserved in pathogenic Leptospira interrogans serovars but absent in non-pathogenic Leptospira biflexa and Leptospira meyeri.
- PCR confirmed the presence of hbpA in all tested clinical isolates of L. interrogans (91 isolates) from diverse geographical origins.
- Anti-HbpA antibodies were detected in the serum of patients diagnosed with leptospirosis.
Conclusions:
- Hemin-binding protein A (HbpA) is a key factor for iron acquisition in pathogenic Leptospira.
- The presence and expression of HbpA in clinical isolates suggest its importance in Leptospira pathogenesis.
- HbpA represents a promising diagnostic marker for leptospirosis.
