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Viable M. leprae as a research reagent.
1Laboratory Research Branch, Hansen's Disease Programs at LSU-SVM, P.O. Box 25072, Baton Rouge, Louisiana 70894, USA. rtrumal@lsu.edu
Summary
Mycobacterium leprae viability can now be rapidly assessed by measuring palmitate oxidation. This radiorespirometry method offers a reliable alternative to the lengthy mouse foot pad (MFP) growth assay for M. leprae research.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Mycobacterium leprae, the causative agent of leprosy, is difficult to culture in vitro.
- Assessing M. leprae viability traditionally relies on the mouse foot pad (MFP) method, which is time-consuming and technically demanding.
Purpose of the Study:
- To evaluate the association between M. leprae's ability to oxidize 14C-palmitate and its viability as determined by the MFP growth assay.
- To establish a more efficient and reliable method for quantifying M. leprae viability.
Main Methods:
- Mycobacterium leprae suspensions were cultured axenically with 14C-palmitate.
- Oxidative activity was measured using radiorespirometry (RR) with biphasic culture vessels or BACTEC 12B vessels.
- Results were compared with M. leprae growth levels obtained from the conventional MFP technique.
Main Results:
- RR results showed a high correlation (r = 0.71) with MFP growth.
- M. leprae viability varied significantly based on host, tissue source, and storage conditions.
- Optimal viability was maintained with short-term storage at 4-33°C; rapid viability loss occurred with freezing or 37°C incubation.
Conclusions:
- Palmitate oxidation via radiorespirometry is a rapid, reliable, and objective method for estimating M. leprae viability.
- This RR method can serve as an effective surrogate for the conventional MFP technique in numerous research applications.
- Understanding M. leprae viability is crucial for leprosy research, and this new method facilitates such studies.