Covid-19 nucleic acid detection, do you choose the right virus preservation solution?

At present, the novel coronavirus control and prevention form is still very severe. As the first step in nucleic acid detection, the importance of sample collection and preservation is beyond doubt. The inspection industry often says "garbage in, garbage out (garbage specimen results)", the most important factor is sampling. If there is a problem with the sample collection, then the following work is done well, and the results are invalid. Choosing the right virus preservation solution and collection tube can make the new crown detection get twice the result with half the effort!

At present, almost all virus preservation solutions on the market directly preserve live viruses, leading to a high risk of infection for medical staff in sampling, transportation and testing. In view of this situation, the first line of anti epidemic disease needs the sample preservation solution which can directly inactivate the virus. However, it should be noted that when inactivating the virus, we should also consider whether the preservation solution can stably preserve the integrity of virus nucleic acid To avoid the degradation of nucleic acid in the sample before detection, resulting in "false negative" of nucleic acid detection. Desheng contains no guanidine salt virus preservation solution to minimize the risk of "false negative".

We compared the effects of preservation solution containing guanidine hydrochloride, guanidine isothiocyanate and guanidine salt free preservatives at 37 ℃. The results showed that the main component was guanidine salt, the preservation effect was not ideal!

Under the same conditions of 37 ℃, the preservation efficiency of viral nucleic acid is basically 100% after 1-7 days of storage; however, the preservation efficiency of viral nucleic acid gradually decreases with the use of other two guanidine salt preservation solutions, and it is lower than 20% by the seventh day, indicating that RNA is undergoing severe degradation over time!

Guanidine salt (guanidine isothiocyanate or guanidine hydrochloride, etc.) is a classical protein denaturant, which is often used for cell lysis in nucleic acid extraction, and can also achieve the effect of virus inactivation. However, guanidine salt does not have the ability to preserve viral nucleic acid at room temperature, which is easy to cause sample degradation. Therefore, it is not suitable for the preservation of new coronavirus samples. Therefore, it is strongly recommended that you choose non guanidine salt Components of the virus preservation solution.

Here, we appeal to the majority of medical workers to pay attention to the following aspects when selecting virus preservation solution if your sampling purpose is nucleic acid detection and you do not need to cultivate live virus:

1. The virus preservation solution can be used to inactivate the virus

At present, nucleic acid detection is to detect the viral RNA in the sample, which needs to split the virus. Therefore, as long as the integrity and stability of the viral nucleic acid can be ensured, there is no need to preserve the live virus. Therefore, in the current situation of fighting against the new coronavirus epidemic situation, it is more ideal to inactivate the virus while collecting samples.

Some manufacturers have introduced inactivated preservation solution on the market, but the inactivated component is guanidine salt. The results of comparative experiments show that guanidine salt preservation solution does not have the ability to preserve virus nucleic acid at room temperature, which is easy to cause sample degradation and is not suitable for the preservation of new coronavirus samples. Therefore, we recommend virus preservation solution containing non guanidine salt protein denaturant It can inactivate the virus and ensure that the virus nucleic acid does not degrade at room temperature.

2. The volume of preservation solution in the sampling tube should be appropriate

It is very important to select the appropriate volume of preservation solution: ① if each sample is sampled separately, it is recommended that you select a virus sampling tube with 1ml preservation solution. The sampling volume can not only meet the requirements of nucleic acid extraction and detection in the downstream, but also the virus concentration is three times higher than that of 3ml preservation solution! ② In case of large-scale preliminary screening and mixed detection, the swab samples of 3-5 people are placed in the same sampling tube. It is recommended that you select a virus sampling tube with 3ml preservation solution, so that the sample size can meet the demand of downstream nucleic acid extraction, improve the detection efficiency and reduce the detection cost.

3. Virus preservation solution that can be used to transport and store samples at room temperature

Because of the instability of RNA, the traditional virus sampling tube needs to be transported to the laboratory within 48 hours under the condition of 4 ℃. If the transportation temperature is not up to the standard, it may cause the degradation of virus nucleic acid and lead to the "false negative" test result! In contrast, if kangweishiji can transport and keep the virus nucleic acid stably at room temperature, the problem of sample transportation can be solved, and the accuracy of detection results can be improved.

4. The virus preservation solution that can protect the sample from high temperature inactivation is used

According to the relevant guidelines of the National Health Commission, the samples should be inactivated at high temperature (above 56 ℃ for 30min) before extracting viral nucleic acid. However, Beijing Center for Disease Control and prevention, Beijing Research Center for preventive medicine and other institutions are in clinical The paper published by chemistry showed that high temperature inactivation could lead to the degradation of viral nucleic acid, thus reducing the detection rate of viral nucleic acid, which was one of the reasons for the high false negative rate of nucleic acid detection of new coronavirus.

The results showed that high temperature inactivation had no significant effect on the integrity of coronavirus nucleic acid.

The virus preservation solution developed and produced by Desheng can be divided into inactivated and non inactivated types. Different preservation solutions are selected according to different experimental requirements and detection conditions. If you have any questions or needs, please call us for details. Choosing Desheng virus preservation solution is your right choice.