• Allen Wing-Ho Chu, Wan-Mui Chan, Jonathan Daniel Ip, Cyril Chik-Yan Yip, Jasper Fuk-Woo Chan, Kwok-Yung Yuen, and Kelvin Kai-Wang To.
• State Key Laboratory for Emerging Infectious Diseases, Carol Yu Centre for Infection, Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
• J. Clin. Virol. 2020 Aug 1; 129: 104519.

BackgroundThe severe shortage of nucleic acid extraction kits during the current COVID-19 pandemic represents a key limiting factor in testing capacity.ObjectivesThis study compared the results of SARS-CoV-2 RT-PCR using different simple nucleic acid extraction methods on nasopharyngeal and saliva specimens.Study DesignFifty nasopharyngeal swab and saliva specimens previously tested positive for SARS-CoV-2 were retrieved. Three different methods of nucleic acid extraction were compared. The first method involves incubating the specimen with proteinase K, and then heat treatment at 98 °C for 5 min (PKH); the second method involves heat treatment at 98 °C for 5 min without proteinase K pre-incubation (heat only); the third method involves no pre-processing steps (direct). The products from all 3 methods were tested by SARS-CoV-2 RT-PCR.ResultsPKH had significantly higher positive rate in SARS-CoV-2 RT-PCR (80 %) than those of heat only (58 %; P = 0.001) or direct (56 %; P = 0.002). The median Ct value was significantly earlier for PKH (median Ct: 37.0, IQR 31.7-40) than that of heat only (median Ct: 40, IQR 36.2-41; P < 0.0001) and direct (median Ct, 37.5; IQR 33.9-41.0; P = 0.0049). Subgroup analysis showed that PKH had higher detection rate, lower limit of detection and earlier Ct values than the other two groups for both NPS and saliva specimens.ConclusionsPKH pre-processing resulted in the highest detection rate of SARS-CoV-2 by RT-PCR, and represents an alternative method for nucleic acid extraction when commercial extraction kits are not available.Copyright © 2020 Elsevier B.V. All rights reserved.

29 keywords...

hide…