Jiankang Zhao*, Yulin Zhang, Bin Cao3
Background: To date, several Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) nucleic acid detection kits are available in China. The virus might have a low load in specimens, resulting in false negative and under diagnosis. Therefore, it is urgently required to evaluate the sensitivities these commonly-used kits.
Methods: Six Real-time Transcription-PCR (RT-PCR) kits for SARS-CoV-2 manufactured in China were evaluated, namely, BGI, Sansure, DaAn, BioGerm, GeneoDx and Liferiver. We used 4 serial dilutions (10-fold) of 7 inactivated samples for the assay, collected from Coronavirus Disease 2019 (COVID-19) patients. Furthermore, the number of positive tests, Limit of Detection (LoD) and Cycle Threshold (CT) values were used to analyze their sensitivities.
Results: For all the 7 samples at original concentration, Samples 1-5 with 10-1 dilution, and Sample 1 with 10-2 dilutions, all 6 kits were positive. The sensitivities of the kits varied with the decreases of nucleic acid concentration. Among the 28 samples, BGI kit obtained 26 positive tests, followed by Sansure, DaAn, BioGerm, GeneoDx, and Liferiver, respectively. Furthermore, LoD of BGI kit was the lowest. Pairwise comparison of average Ct values of the above 6 kits revealed that BGI had the most significantly lower CT values for ORF 1ab gene, whereas Sansure had better performance for the detection of N gene.
Conclusions: All 6 kits can provide accurate detection results in the clinical samples with high viral loads. BGI kit was the most sensitive kits. Each kit had its own advantages and disadvantages, and further optimization is needed.