The impacts of viral inactivating methods on quantitative RT-PCR for COVID-19

Objective: This paper aims to explore the effect of four virus inactivation methods on the rapid detection results of COVID-19 nucleic acid. Methods: Collected samples of nasopharyngeal swabs from 2 patients diagnosed with COVID-19 at the First People's Hospital of Zhaoqing City, each of sample was divided into 5 groups (groupA similar to E): A:Non-inactivated raw sample; B:75 % ethanol inactivation; C:56 degrees C incubation for 30 min inactivation; D:65 degrees C incubation for 10 min inactivation; E:Pre-inactivation using RNA virus special preservation fluid added into the sampling tube to treated the nasopharyngeal swab sample separately, using real-time fluorescent RT-PCR to detect the N gene of COVID-19 and the ORFlab gene simultaneously. All the groups are diluted in 1:2, 1:4, 1:8 ratios. The objectives are to compare the effect of the varied inactivation method on CT(Cycle Threshold)results in PCR, conduct correlation and Bland-Altman analysis. Results: For the N gene and ORF1ab gene, the CT values of 4 inactivated and Non-inactivated treatment were correlated (P < 0.001). The results of the four treatment methods and specimens without inactivated treatment have shown good consistency. Conclusion: The treatment of nasopharyngeal swab specimens using mentioned four inactivated methods had no significant effect on the subsequent detection of the new COVID-19 nucleic acid test. Lab test-persons can flexibly adopt pre-inactivation methods to ensure the accuracy of virus nucleic acid test results, meanwhile guarantee the safety of lab test-persons.