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Optimized Protocols for Mycobacterium leprae Strain Management: Frozen Stock Preservation and Maintenance in Athymic Nude Mice
Published on: March 23, 2014
PROLONGED MAINTENANCE OF SPIROCHETES AND FILTRABLE VIRUSES IN THE FROZEN STATE
1Department of Bacteriology of The Johns Hopkins School of Hygiene and Public Health, Baltimore.
Abstract:
1. Observations are reported on the virulence of various types of spirochetes and filtrable viruses after storage at - 787deg;C. for periods up to 3 years. 2. Five specimens of Treponema pallidum belonging to 4 different strains, and 7 specimens of T. pertenue belonging to 5 different strains were tested after storage for approximately 3 years. With one exception each specimen contained actively motile treponemes, and all specimens were highly pathogenic for rabbits. Many other specimens of these spirochetes stored for shorter periods were also tested with similar results. 3. Relapsing fever spirochetes tested after storage from 6 months to 1 year showed active motility and were virulent for mice. 4. Leptospira icterohemorrhagiae was found to be actively motile after storage for 5, 6, and 10 months. The spirochete of rat bite fever, Spirillum minus, was virulent for mice after storage for 1 year. 5. The virus of human influenza, PR8 strain, tested after storage for approximately 3 years was fatal to mice in essentially the same dilution as was the same lot of material before freezing. Similar results were obtained upon testing the virus of meningopneumonitis after storage for 3 years. The virus of lymphogranuloma inguinale was pathogenic for mice after storage for 10 months.
Insights
Spirochetes and viruses, including Treponema pallidum and influenza virus, remain virulent and infectious after up to three years of frozen storage. Cryopreservation effectively preserves the pathogenicity of these microbial agents for research purposes.
Area of Science:
- Microbiology
- Virology
- Infectious Diseases
Background:
- Cryopreservation is a critical technique for preserving biological samples.
- Understanding the long-term viability of pathogens post-cryopreservation is essential for research and diagnostics.
Purpose of the Study:
- To evaluate the virulence and motility of various spirochetes and viruses after prolonged storage at -78.7°C.
- To determine the stability of pathogenic microorganisms under cryogenic conditions.
Main Methods:
- Spirochetes (Treponema pallidum, T. pertenue, relapsing fever spirochetes, Leptospira icterohemorrhagiae, Spirillum minus) and viruses (human influenza, meningopneumonitis, lymphogranuloma inguinale) were stored at -78.7°C for up to 3 years.
- Post-storage, motility was assessed, and virulence was tested in animal models (rabbits and mice).
Main Results:
- Treponema pallidum and T. pertenue remained motile and highly pathogenic for rabbits after approximately 3 years of storage.
- Relapsing fever spirochetes, Leptospira icterohemorrhagiae, and Spirillum minus retained motility and virulence for mice after 6 months to 1 year of storage.
- Influenza virus (PR8 strain), meningopneumonitis virus, and lymphogranuloma inguinale virus maintained infectivity and pathogenicity for mice after 3 years and 10 months of storage, respectively.
Conclusions:
- Cryopreservation at -78.7°C is an effective method for maintaining the virulence and motility of a wide range of spirochetes and viruses for extended periods.
- These findings support the use of long-term frozen storage for microbial pathogens in research and diagnostic applications.
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