Virus Cryopreservation


Virus snap freezing is the technique in which a virus specimen is rapidly frozen using dry ice, a dry ice/ethanol slurry or liquid nitrogen.  Snap freezing reduces the chance of water present in the sample forming ice crystals during the freezing process, and better maintains the integrity of the virus sample.  This method can provide excellent specimen integrity and a wide array of options for analysis, including extraction of proteins, DNA and RNA for use in research and diagnostics.



Typically, virus samples are collected in either microfuge tubes or cryogenic vials and placed directly into dry ice or into a slurry of dry ice and ethanol.  This method does not allow for good organization of the sample vials and results in potentially variable sample freezing rates.  Further, it is often difficult to see white tubes in dry ice and samples can be inadvertently lost of omitted from sample sets.

BioCision's CoolRack® thermo-conductive sample modules provide an easy and inexpensive solution.  The modules, when placed on dry ice, rapidly adapt to the dry ice temperature and snap freeze vials that are inserted into it in a consistent, organized and reproducible manner.


Snap freezing in dry ice
Current method of snap freezing virus samples in dry ice. The random layout can result in misidentification and errors in processing, and non-uniform dry ice contact can result in freezing variability.

Snap freezing in dry ice using a CoolRack

CoolRack tube modules rapidly adapt to the dry ice temperature (-78ºC), allowing you to snap freeze your virus samples without direct contact with dry ice. Samples stay organized and freeze upright and uniformly. CoolRack modules can also be used in liquid nitrogen.



Snap freezing in dry ice

Virus titer data comparing samples frozen directly in alcohol-dry ice slurry and in a CoolRack placed on dry ice.  Titer results were equivalent, however, using a CoolRack module on dry ice provided organization, consistency and efficient workflow. (Left)


Type of Tube

CoolRack (# of samples)

CoolRack Catalog #

Ice Pan

Microfuge, 1.5 or 2.0 ml

CoolRack M6 (6)

CoolRack M15 (15)

CoolRack M30 (30)

CoolRack M90 (90)

CoolRack M96 (96)






1L Mini Ice Pan

1L Mini ice Pan

4L Midi Ice Pan

9L Maxi Ice Pan

9L Maxi Ice Pan

Cryogenic vials

CoolRack CF15 (15)

CoolRack CFT30 (30)

CoolRack CF45 (45)




1L Mini Ice Pan

4L Midi Ice Pan

4L Midi Ice Pan

Centrifuge tubes

CoolRack 15ml (9)

CoolRack 50ml (4)



4L Midi Ice Pan

4L Midi Ice Pan

*All CoolRack modules are compatible with dry ice and LN2. CLICK HERE to select a CoolRack for your specific need.


Quick Protocol:

Snap Freezing Virus Samples with CoolRack modules

    • 1)  Place pelleted or crushed dry ice in your ice pan
    • 2)  Place CoolRack module of choice on top of the dry ice for 5-7 minutes to equilibrate to temperature of dry ice
    • 3)  Place your samples in CoolRack module and wait 3-4 minutes

    • Depending upon your sample, freezing can be complete within 3-4 minutes, but we suggest waiting for the full ten minutes before transferring to a -80°C freezer or liquid nitrogen.  Always refer to your laboratory SOP for handling your specific virus species or strain.




Virus Cryopreservation Using a CoolRack Module >


Snap Freezing Samples in Dry Ice Using a CoolRack Module >


Learn more about:

CoolRack thermo-conductive tube

Ice pans and buckets
made from non-toxic EVA foam

vial grabbers to protect fingers from frozen vials >