PROLONGED MAINTENANCE OF SPIROCHETES AND FILTRABLE VIRUSES IN THE FROZEN STATE

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.