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Proteomic analysis of Leptospira interrogans shed in urine of chronically infected hosts
Avril M Monahan1, John J Callanan, Jarlath E Nally
1Veterinary Sciences Centre, UCD School of Agriculture Food Science & Veterinary Medicine, College of Life Sciences, University College Dublin, Belfield, Dublin 4, Ireland.
Abstract:
Leptospirosis is a global zoonotic disease. The causative agent, pathogenic Leptospira species, survives in the renal tubules of chronically infected hosts, from where leptospires are shed via urine into the environment. Infection of new hosts can present as an array of acute and chronic disease processes reflecting variations in host-pathogen interactions. The present study was designed to reproduce the carrier phase of infection in Rattus norvegicus, thus facilitating shedding of leptospires in urine. Leptospires shed in urine were collected for proteomic analysis because these organisms reflect a naturally virulent form of Leptospira associated with infection of new hosts. Experimentally infected rats remained clinically asymptomatic but shed leptospires in urine for several months at concentrations of up to 10(7) leptospires/ml of urine. Proteomic analysis of rat urine-isolated leptospires compared to in vitro-cultivated leptospires confirmed differential protein and antigen expression, as demonstrated by two-dimensional gel electrophoresis and immunoblotting. Furthermore, while serum from chronically infected rats reacted with many antigens of in vitro-cultivated Leptospira, few antigens of rat urine-isolated Leptospira were reactive. Results confirm that differential protein expression by Leptospira during chronic infection facilitates its persistence in the presence of a specific host antibody response.
Insights
Chronic Leptospira infection in rats leads to asymptomatic shedding of the bacteria in urine. This study reveals that Leptospira alters its protein expression during chronic infection, evading the host
Area of Science:
- Microbiology
- Infectious Diseases
- Zoonotic Diseases
Background:
- Leptospirosis is a significant global zoonotic disease caused by pathogenic Leptospira species.
- Leptospires establish chronic infections in host renal tubules, leading to urinary shedding and environmental contamination.
- Host-pathogen interactions influence the diverse clinical presentations of leptospirosis.
Purpose of the Study:
- To replicate the carrier phase of Leptospira infection in rats (Rattus norvegicus).
- To collect and analyze leptospires shed in urine, representing a virulent form associated with new host infections.
- To investigate differential protein expression in leptospires during chronic infection.
Main Methods:
- Experimental infection of rats to induce a chronic carrier state with urinary shedding.
- Collection of leptospires from rat urine for proteomic analysis.
- Comparison of urine-isolated leptospires with in vitro-cultivated leptospires using two-dimensional gel electrophoresis and immunoblotting.
Main Results:
- Experimentally infected rats remained asymptomatic but shed high concentrations of leptospires in urine for months.
- Proteomic analysis revealed significant differences in protein and antigen expression between urine-isolated and in vitro-cultivated leptospires.
- Serum from infected rats showed reduced reactivity to antigens from urine-isolated leptospires compared to in vitro-cultivated ones.
Conclusions:
- Differential protein expression by Leptospira is crucial for its persistence during chronic infection.
- Altered antigen expression allows leptospires to evade host antibody responses, facilitating long-term survival.
- Understanding these mechanisms is key to controlling the spread of leptospirosis.
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