BACKGROUND: Upper respiratory samples used to test for SARS-CoV-2 virus may be infectious and present a hazard during transport and testing. A buffer with the ability to inactivate SARS-CoV-2 at the time of sample collection could simplify and expand testing for COVID-19 to non-conventional settings. METHODS: We evaluated a guanidium thiocyanate-based buffer, eNAT™ (Copan) as a possible transport and inactivation medium for downstream RT-PCR testing to detect SARS-CoV-2. Inactivation of SARS-CoV-2 USA-WA1/2020 in eNAT and in diluted saliva was studied at different incubation times. The stability of viral RNA in eNAT was also evaluated for up to 7 days at room temperature (28°C), refrigerated conditions (4°C) and at 35°C. RESULTS: SARS-COV-2 virus spiked directly in eNAT could be inactivated at >5.6 log 10 PFU/ml within a minute of incubation. When saliva was diluted 1:1 in eNAT, no cytopathic effect (CPE) on vero-E6 cell lines was observed, although SARS-CoV-2 RNA could be detected even after 30 min incubation and after two cell culture passages. A 1:2 (saliva:eNAT) dilution abrogated both CPE and detectable viral RNA after as little as 5 min incubation in eNAT. SARS-CoV-2 RNA from virus spiked at 5X the limit of detection remained positive up to 7 days of incubation in all tested conditions. CONCLUSION: eNAT and similar guanidinium thiocyanate-based media may be of value for transport, preservation, and processing of clinical samples for RT-PCR based SARS-CoV-2 detection.
BACKGROUND: Upper respiratory samples used to test for SARS-CoV-2 virus may be infectious and present a hazard during transport and testing. A buffer with the ability to inactivate SARS-CoV-2 at the time of sample collection could simplify and expand testing for COVID-19 to non-conventional settings. METHODS: We evaluated a guanidium thiocyanate-based buffer, eNAT™ (Copan) as a possible transport and inactivation medium for downstream RT-PCR testing to detect SARS-CoV-2. Inactivation of SARS-CoV-2 USA-WA1/2020 in eNAT and in diluted saliva was studied at different incubation times. The stability of viral RNA in eNAT was also evaluated for up to 7 days at room temperature (28°C), refrigerated conditions (4°C) and at 35°C. RESULTS: SARS-COV-2 virus spiked directly in eNAT could be inactivated at >5.6 log 10 PFU/ml within a minute of incubation. When saliva was diluted 1:1 in eNAT, no cytopathic effect (CPE) on vero-E6 cell lines was observed, although SARS-CoV-2 RNA could be detected even after 30 min incubation and after two cell culture passages. A 1:2 (saliva:eNAT) dilution abrogated both CPE and detectable viral RNA after as little as 5 min incubation in eNAT. SARS-CoV-2 RNA from virus spiked at 5X the limit of detection remained positive up to 7 days of incubation in all tested conditions. CONCLUSION: eNAT and similar guanidinium thiocyanate-based media may be of value for transport, preservation, and processing of clinical samples for RT-PCR based SARS-CoV-2 detection.
Authors: Michael J Loeffelholz; David Alland; Susan M Butler-Wu; Utsav Pandey; Carlo Frederico Perno; Alice Nava; Karen C Carroll; Heba Mostafa; Emma Davies; Ashley McEwan; Jennifer L Rakeman; Randal C Fowler; Jean-Michel Pawlotsky; Slim Fourati; Sukalyani Banik; Padmapriya P Banada; Shobha Swaminathan; Soumitesh Chakravorty; Robert W Kwiatkowski; Victor C Chu; JoAnn Kop; Rajiv Gaur; Mandy L Y Sin; Duy Nguyen; Simranjit Singh; Na Zhang; David H Persing Journal: J Clin Microbiol Date: 2020-07-23 Impact factor: 5.948
Authors: Jennifer Harcourt; Azaibi Tamin; Xiaoyan Lu; Shifaq Kamili; Senthil K Sakthivel; Janna Murray; Krista Queen; Ying Tao; Clinton R Paden; Jing Zhang; Yan Li; Anna Uehara; Haibin Wang; Cynthia Goldsmith; Hannah A Bullock; Lijuan Wang; Brett Whitaker; Brian Lynch; Rashi Gautam; Craig Schindewolf; Kumari G Lokugamage; Dionna Scharton; Jessica A Plante; Divya Mirchandani; Steven G Widen; Krishna Narayanan; Shinji Makino; Thomas G Ksiazek; Kenneth S Plante; Scott C Weaver; Stephen Lindstrom; Suxiang Tong; Vineet D Menachery; Natalie J Thornburg Journal: Emerg Infect Dis Date: 2020-06-17 Impact factor: 6.883
Authors: David van Bockel; C Mee Ling Munier; Stuart Turville; Steven G Badman; Gregory Walker; Alberto Ospina Stella; Anupriya Aggarwal; Malinna Yeang; Anna Condylios; Anthony D Kelleher; Tanya L Applegate; Andrew Vallely; David Whiley; William Rawlinson; Phillip Cunningham; John Kaldor; Rebecca Guy Journal: Viruses Date: 2020-10-23 Impact factor: 5.048