THE PRESERVATION OF VIRULENT TREPONEMA PALLIDUM AND TREPONEMA PERTENUE IN THE FROZEN STATE; WITH A NOTE ON THE...

Area of Science:

• Microbiology
• Virology
• Cryobiology

Background:

• Maintaining the viability and infectivity of pathogenic microorganisms and viruses is crucial for research and diagnostics.
• Standard preservation methods can lead to loss of morphology, motility, and virulence.
• Effective cryopreservation techniques are needed for long-term storage of Treponema species and various viruses.

Purpose of the Study:

• To describe a simple and effective method for freezing and maintaining tissue specimens, specifically focusing on Treponema pallidum and Treponema pertenue.
• To evaluate the viability, morphology, motility, and virulence of Treponema species after prolonged storage at -78°C.
• To assess the stability of certain viruses, including influenza and yellow fever, under the same cryopreservation conditions.

Main Methods:

• A cryopreservation method utilizing a mixture of solid carbon dioxide (dry ice) and 95% ethyl alcohol, achieving temperatures around -78°C.
• Freezing and maintaining various strains of Treponema pallidum and Treponema pertenue at -78°C for periods up to one year.
• Testing the morphology, motility, and infectivity (virulence in rabbits) of thawed treponemes.
• Assessing the viral titer of human influenza, yellow fever, and mouse encephalomyelitis viruses after storage at -78°C for six months.

Main Results:

• Treponema pallidum and Treponema pertenue maintained normal morphology, motility, and virulence for rabbits after at least one year of storage at -78°C.
• Cryopreservation at -10°C and -20°C resulted in treponeme death within two months, with death occurring during the maintenance phase.
• Treponemes generally did not survive freezing and desiccation, although limited infectivity was observed one day post-desiccation for T. pallidum.
• Viruses of human influenza, yellow fever, and mouse encephalomyelitis retained their titers after six months of storage at -78°C.

Conclusions:

• The described method of freezing at -78°C is highly effective for the long-term preservation of Treponema species, maintaining their biological activity.
• Cryopreservation at less extreme temperatures (-10°C to -20°C) is insufficient for long-term survival of these treponemes.
• The -78°C method is also suitable for preserving the infectivity of certain viruses, offering a valuable tool for research and diagnostics.