Question

Specimen preservation and storage: Unpreserved viruses may be stored at 4℃; however, if they are to be stored for greater than 24hrs, viruses should be frozen at ________℃.

a) -20
b) -70
c) -80
d) -196

Answer 1

Viruses that need to be stored for more than 24 hours should be frozen at -80℃ to ensure their long-term preservation. Option c.

Step-by-step explanation:

Unpreserved viruses that require long-term storage should generally be frozen at very low temperatures. The correct temperature for storage, when longer than 24 hours is needed, is given by option (c) -80℃. This temperature allows for the preservation of the viruses over a long period without significant loss of viability.

Laboratory cultures or medical specimens, including viruses, are often stored at ultra-low temperatures, which can be either at -70℃ using ultra-low freezers or down to -196℃ in liquid nitrogen tanks, which is usually for cell preservation rather than viruses.

For efficient and safe preservation, it is crucial to pay attention to specifics such as the freeze-thaw cycle and the type of medium used, with some protocols citing the use of protective agents like glycerol or dimethyl sulfoxide (DMSO) to protect the specimens against freezing damage.

Option c.