key: cord-0940068-insbmoti authors: Batéjat, Christophe; Grassin, Quentin; Manuguerra, Jean-Claude; Leclercq, India title: Heat inactivation of the Severe Acute Respiratory Syndrome Coronavirus 2 date: 2021-01-23 journal: J Biosaf Biosecur DOI: 10.1016/j.jobb.2020.12.001 sha: 525f680a5b44394ce9afd9291fdca34ccdbe2b2d doc_id: 940068 cord_uid: insbmoti Supernatants of cells infected with SARS-CoV-2, and nasopharyngeal and sera samples containing SARS-CoV-2 were subjected to heat inactivation for various periods of time, ranging from 30 s to 60 min. Our results showed that SARS-CoV-2 could be inactivated in less than 30 min, 15 min, and 3 min at 56 °C, 65 °C, and 95 °C, respectively. These data could help laboratory workers to improve their protocols by handling the virus in biosafety conditions. 13 Supernatants of cells infected with SARS-CoV-2, and nasopharyngeal, and sera samples 14 containing SARS-CoV-2 were subjectedsubmitted to heat inactivation for various periods of 15 time, ranging from 30 sseconds to 60 minminutes. Our results showed that SARS-CoV-2 could 16 be inactivated in less than 30 minminutes, 15 min,minutes and 3 minminutes at 56 °C, 65 °C, 17 and 95 °C, respectively. These data could help laboratory workers to improve their protocols 18 bywith handling of the virus in biosafety conditions. It has been a pleasure working on your manuscript. I wish you the best in its publication and in all your future scientific endeavors. : I believe this should be rewritten as "Cell culture medium, nasopharyngeal, and sera samples containing SARS-CoV-2…" This is because, to my understanding, you grew the virus on Vero E6 cells and, prior to the experiments on heat inactivation, you took supernatants containing the virus and adjusted the viral titer to 6 log10 TCID50/mL in cell culture medium, nasopharyngeal samples, and sera. Hence, if this is correct, all samples contain supernatants from infected cells. Please revise whether my suggestion is appropriate. The part "already caused an increasing number" sounds rather awkward. Please consider this alternative. facing new challenges to combatfight the ongoing outbreak. As no specific therapeutics and 26 vaccines are available for disease control, countries lockdowns, social distancing, and quick In this study, we tested three3 different inactivation temperatures ( i.e. 56°C, 65°C, and 95°C), Although 56 °C the former being is commonly used for inactivation of enveloped viruses 2,3 , 39 although higher temperatures can be used for some viruses in some cases 4-6 . This temperature 40 is also used tofor eliminateelimination of serum complement. In this study, We we exposed the 41 SARS-CoV-2 to these three different inactivation temperatures (56 °C, 65 °C, and 95 °C) during 42 for various periods of time and tested its infectivity using theby TCID 50 method. A human strain of SARS-CoV-2, isolated from a French patient hospitalized in February 2020 44 (GISAID accession number: EPI_ISL_437689), was grown on Vero E6 cells for three passages. The cells were maintained in Dulbecco's modified Eagle's medium (DMEM 1X, GIBCO) and 46 supplemented with 5% fetal calf serum (FCS) and, antibiotics (0.1 units penicillin, 0.1 mg/mL 47 streptomycin, GIBCO) at 37 °C in a humidified 5% CO 2 incubator. The SARS-CoV-2 virus 48 was titrated by the TCID 50 method, as described previously 7 , except that Vero E6 cells were 49 used and examination for cytopathic effect was performed after 5 days. The virus with a al titer The original sentence had a rather awkward structure, making it unnecessarily complex. : I find that this text unnecessarily increases the complexity of the sentence. This compromises the readability of the text. Aim at simple, straightforward sentences. You have already indicated that it is not always the case by using the word "sometimes." Commented [A7]: I believe this sentence is misplaced here. Please see below. The terms former and latter are words used to distinguish between two things. Former directs us to the first of these two things, and latter directs us to the second (or last) of them. Do not use former or latter when you are writing about more than two things. This has been changed to avoid repeating the word virus. This sentence contains all the information that was present in the first line of this paragraph. Thus, that line has been deleted to avoid redundancy. of was adjusted from 6.5 log 10 TCID 50 /mL was adjusted to a final titer of 6 log 10 TCID 50 /mL in If this is correct, I find this to be confusing, as the text may suggest that you were comparing viruses from three different types of samples: cell cultures, nasopharyngeal samples, and sera. If what I am saying is correct, you should consider changing it to "spiked cell culture medium, nasopharyngeal, and sera samples," which will make the text clearer. Please revise whether my suggestion is appropriate. were used as previously described 8 . The E gene was used as a tertiary target for confirmation, 75 following the Charité protocol 9 . The results showed that the mean genomic RNA copy number 76 ranged between 9.9 x 10 7 copy genome/5 µL and 5.3 x 10 9 copy genome/5 µL (data not shown). For each condition, the quantity of viral RNA was very stable over time, suggesting that viral CRediT author statement East respiratory syndrome coronavirus. Influenza Other Respir Viruses Use of heat inactivated viral haemorrhagic 106 fever antigens in serological assays pandemic influenza A (H1N1) virus in water and on non-porous 110 surface Detection of 2019 novel coronavirus (2019-116 nCoV) by real-time RT-PCR Viral load of SARS-CoV-2 in clinical 119 samples Virological assessment of hospitalized 121 patients with COVID-2019 Stability of SARS-CoV-2 in different 124 environmental conditions Aerosol and Surface Stability of 127 SARS-CoV-2 as Compared with SARS-CoV-1