Effects of inactivation method on SARS-CoV-2 virion proteins and structure

The risk posed by Severe Acute Respiratory Syndrome Coronavirus -2 (SARS-CoV-2) dictates that live-virus research is conducted in a biosafety level 3 (BSL3) facility. Working with SARS-CoV-2 at lower biosafety levels can expedite research yet requires the virus to be fully inactivated. In this study, we validated and compared two protocols for inactivating SARS-CoV-2: heat treatment and ultraviolet irradiation. The two methods were optimized to render the virus completely incapable of infection while limiting destructive effects of inactivation. We observed that 15 minutes of incubation at 65{degrees}C completely inactivates high titer viral stocks. Complete inactivation was also achieved with minimal amounts of UV power (70,000 J/cm2), which is 100-fold less power than comparable studies. Once validated, the two methods were then compared for viral RNA quantification, virion purification, and antibody recognition. We observed that UV irradiation resulted in a 2-log reduction of detectable genomes compared to heat inactivation. Protein yield following virion enrichment was equivalent for all inactivation conditions, but the resulting viral proteins and virions were negatively impacted by inactivation method and time. We outline the strengths and weaknesses of each method so that investigators might choose the one which best meets their research goals.