1. Assessment of SARS-CoV-2 infectivity of upper respiratory specimens from COVID-19 patients by virus isolation using VeroE6/TMPRSS2 cells
- Author
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Tadaki Suzuki, Souichi Yamada, Shuetsu Fukushi, Hitomi Kinoshita, Makoto Ohnishi, Tsuguto Fujimoto, Masayuki Saijo, Ken Maeda, Nozomu Hanaoka, Naomi Nojiri, Ai Kawana-Tachikawa, Shigeru Kusagawa, Koichi Ishikawa, Shigeyoshi Harada, Saori Matsuoka, Tadashi Kikuchi, Sayuri Seki, Midori Nakamura-Hoshi, Shoji Miki, Lucky Ronald Runtuwene, Nobuo Koizumi, Sunao Iyoda, Hideyuki Takahashi, Hidemasa Izumiya, Jiro Mitobe, Shouji Yamamoto, Masatomo Morita, Ken-ichi Lee, Ken Shimuta, Kyoko Saito, Masayoshi Fukasawa, Yasutaka Hoshino, Ken Miyazawa, Minoru Nagi, Chikako Shimokawa, Yasuyuki Morishima, Takashi Sakudoh, Yoshihiro Kaku, Chang Kweng Lim, Shigeru Tajima, Takahiro Maeki, Eri Nakayama, Satoshi Taniguchi, Motohiko Ogawa, Takanobu Kato, Hussein Hassan Aly, Kousho Wakae, and Kento Fukano
- Subjects
Pulmonary and Respiratory Medicine ,viruses ,Respiratory Infection ,medicine.disease_cause ,Virus ,Cell Line ,Specimen Handling ,Diseases of the respiratory system ,03 medical and health sciences ,0302 clinical medicine ,Cytopathogenic Effect, Viral ,Nasopharynx ,Chlorocebus aethiops ,Animals ,Humans ,Medicine ,030212 general & internal medicine ,Respiratory system ,Saliva ,Vero Cells ,Coronavirus ,Infectivity ,0303 health sciences ,RC705-779 ,SARS-CoV-2 ,030306 microbiology ,business.industry ,Transmission (medicine) ,Serine Endopeptidases ,COVID-19 ,Outbreak ,Virology ,COVID-19 Nucleic Acid Testing ,Vero cell ,viral infection ,Nasal Cavity ,business ,Viral load - Abstract
BackgroundAn outbreak of novel coronavirus (SARS-CoV-2)-associated respiratory infectious diseases (COVID-19) emerged in 2019 and has spread rapidly in humans around the world. The demonstration of in vitro infectiousness of respiratory specimens is an informative surrogate for SARS-CoV-2 transmission from patients with COVID-19; accordingly, viral isolation assays in cell culture are an important aspect of laboratory diagnostics for COVID-19.MethodsWe developed a simple and rapid protocol for isolating SARS-CoV-2 from respiratory specimens using VeroE6/TMPRSS2 cells, a cell line that is highly susceptible to the virus. We also investigated a correlation between isolation of SARS-CoV-2 and viral load detected by real-time RT-PCR (rRT-PCR) using N2 primer/probe set that has been developed for testing of COVID-19 in Japan.ResultsThe SARS-CoV-2 isolation protocol did not require blind passage of inoculated cells and yielded the results of viral isolation within 7 days after inoculation. Specimens with cycle threshold (Ct) values of 35 were virus isolation-positive, indicating that low viral loads (high Ct values) in upper respiratory specimens do not always indicate no risk of containing transmissible virus.ConclusionIn combination with rRT-PCR, the SARS-CoV-2 isolation protocol provides a means for assessing the potential risk of transmissible virus in upper respiratory specimens.
- Published
- 2021
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