Heat Inactivation of Different Types of SARS-CoV-2 Samples: What Protocols for Biosafety, Molecular Detection and Serological Diagnostics?

• Main Authors: Boris Pastorino, Franck Touret, Magali Gilles, Xavier de Lamballerie, Remi N. Charrel
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Viruses
• Subjects: SARS-CoV-2; coronavirus; heat inactivation; COVID-19; serology; ELISA
• Online Access: https://www.mdpi.com/1999-4915/12/7/735

Standard precautions to minimize the risk of SARS-CoV-2 transmission implies that infected cell cultures and clinical specimens may undergo some sort of inactivation to reduce or abolish infectivity. We evaluated three heat inactivation protocols (56 °C-30 min, 60 °C-60 min and 92 °C-15 min) on SARS-CoV-2 using (i) infected cell culture supernatant, (ii) virus-spiked human sera (iii) and nasopharyngeal samples according to the recommendations of the European norm NF EN 14476-A2. Regardless of the protocol and the type of samples, a 4 Log₁₀ TCID50 reduction was observed. However, samples containing viral loads > 6 Log₁₀ TCID₅₀ were still infectious after 56 °C-30 min and 60 °C-60 min, although infectivity was < 10 TCID₅₀. The protocols 56 °C-30 min and 60 °C-60 min had little influence on the RNA copies detection, whereas 92 °C-15 min drastically reduced the limit of detection, which suggests that this protocol should be avoided for inactivation ahead of molecular diagnostics. Lastly, 56 °C-30 min treatment of serum specimens had a negligible influence on the results of IgG detection using a commercial ELISA test, whereas a drastic decrease in neutralizing titers was observed.