Impact of pooling of inactivated SARS-CoV-2 samples on nucleic acid detection / 公共卫生与预防医学

ABSTRACT

Objective To investigate the impact of pooling of inactivated samples on testing results of nucleic acid detection of SARS-CoV-2, and to provide a scientific detection scheme for the SARS-CoV-2 nucleic acid screening of large population samples. Methods The SARS-CoV-2 positive throat swab samples and the negative throat swab samples were inactivated at 56°C for 30 minutes, and mixed according to the ratio of positive samples to negative samples at 14, 19, and 119, respectively. Real-time fluorescent RT-PCR technology was used to detect the ORF-lab and N genes in the original solution and mixed solution. Results The nucleic acid test results of the 20 groups of inactivated samples were all positive. The nucleic acid test results of the 15 mixture and the 110 mixture were also positive. One group of samples of the 120 mixture was negative for ORF-lab and positive for the N gene. The Ct values of nucleic acid detection among all groups were significantly correlated. There was no statistically significant difference in the positive rate between different sample groups. Compared with the original solution, the Ct values of the ORF-lab gene of 15 mixture, 110 mixture, and 120 mixture samples increased by 1.73, 2.86, and 4.05, respectively, while the Ct values of the N gene of 15 mixture, 110 mixture and 120 mixture samples increased by 1.69, 2.79, and 3.25, respectively. Conclusion When conducting nucleic acid screening for SARS-CoV-2 in large population samples, a mixed test of less than 10 inactivated samples would not affect the qualitative results in most cases, but the results of weak positive samples may be affected.