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Updated: May 23, 2026
Optimized Protocols for Mycobacterium leprae Strain Management: Frozen Stock Preservation and Maintenance in Athymic Nude Mice
Published on: March 23, 2014
Development of a mouse food pad model for detection of sub clinical leprosy
Ramanuj Lahiri1, Baljit Randhawa, Kees L M C Franken
1Department of Health and Human Services, Health Resources and Services Administration, Bureau of Primary Health Care, National Hansen's Disease Program, Baton Rouge, LA, USA.
Abstract:
Early diagnosis of leprosy and a multi-drug therapy (MDT) regimen will block the trajectory of nerve damage, disability and deformity that are the hallmarks of this chronic disease. However, the diagnosis of leprosy is made solely by recognition of clinical signs and symptoms, requiring special expertise. These limitations also result in the under reporting of worldwide prevalence and incidence rates for leprosy. Sorely needed is an objective laboratory test for detecting early leprosy. As the antigenic burden of M. leprae can be virtually undetectable in early clinical leprosy, cell mediated immunity and antibody responses will likely be weak. So the sensitivity of new diagnostic tests is as important as specificity. Major efforts are underway employing recombinant M. leprae antigens and synthetic peptides, to develop diagnostic assays for early leprosy infection, using in vitro T cell reactivity or serological tests. We have used the initial phase of the mouse foot pad model as an 'early' model of leprosy infection to screen T cell responses against M. leprae specific antigens and synthetic peptides. Unlike human disease in animal models we can control infection progress and monitor bacillary growth relative to time course of development of T cell response to specific M. leprae antigens. The study employed splenic T cells instead of draining lymph node T cells to model the systemic response as opposed to a local one. We found that 10(5) live M. leprae is the minimum dose required for any meaningful and consistent in vitro splenic IFN-gamma response against M. leprae antigens 3 months after foot pad inoculation. Using this model we found that several M. leprae recombinant proteins, ML0840, ML2028, ML2307, ML2346, ML2478, and ML2532, induced significant levels of IFN-gamma secretion. By controlling for variables that can be confounding factors in the sensitivity of human testing, this mouse model provides an interface between M. leprae diagnostic antigen development and the screening of these antigens in humans under field conditions.
Insights
Developing an objective laboratory test for leprosy is crucial for early diagnosis and preventing nerve damage. This study identified specific Mycobacterium leprae antigens that elicit a measurable immune response in a mouse model, paving the way for new diagnostic tools.
Area of Science:
- Immunology
- Infectious Diseases
- Microbiology
Background:
- Leprosy diagnosis relies on clinical signs, leading to underreporting and delayed treatment, which allows nerve damage to progress.
- Current diagnostic methods lack objectivity and sensitivity for early leprosy detection, necessitating the development of reliable laboratory tests.
- Effective early diagnosis and multi-drug therapy (MDT) are essential to prevent the characteristic nerve damage, disability, and deformity associated with leprosy.
Purpose of the Study:
- To develop and validate an objective laboratory test for early leprosy detection.
- To screen Mycobacterium leprae (M. leprae) specific antigens and synthetic peptides for their ability to elicit a cell-mediated immune response.
- To establish a reliable animal model for evaluating diagnostic antigens under controlled conditions.
Main Methods:
- Utilized a mouse foot pad model to simulate early leprosy infection and assess T cell responses.
- Screened splenic T cells for Interferon-gamma (IFN-gamma) secretion in response to M. leprae antigens and synthetic peptides.
- Determined the minimum infectious dose (10^5 live M. leprae) required for a consistent IFN-gamma response in the mouse model.
Main Results:
- Identified several M. leprae recombinant proteins (ML0840, ML2028, ML2307, ML2346, ML2478, ML2532) that induced significant IFN-gamma secretion.
- Demonstrated a consistent splenic T cell response three months post-inoculation with a minimum dose of 10^5 live M. leprae.
- The mouse model allowed for controlled monitoring of bacillary growth and T cell responses, mitigating confounding factors seen in human studies.
Conclusions:
- The identified M. leprae antigens show promise for developing sensitive and specific diagnostic assays for early leprosy.
- The mouse foot pad model serves as a valuable platform for screening diagnostic antigens before human field trials.
- Objective laboratory tests are critical for improving leprosy surveillance and enabling timely intervention to prevent long-term complications.
