Effect of Heat Inactivation and Bulk Lysis on Real-Time Reverse Transcription PCR Detection of the SARS-COV-2: an Experimental Study

The outbreak of the severe acute respiratory syndrome coronavirus - 2 has quickly turned into a global pandemic. Real-time reverse transcription Polymerase chain reaction is commonly used to diagnose as gold standard. Many coronaviruses are sensitive to heat and chemicals. Heat and chemical inactivation of samples is considered a possible method to reduce the risk of transmission, but the effect of heating and chemical treatment on the measurement of the virus is still unclear. Thus, this study aimed to investigate the effect of heat inactivation and chemical bulklysis on virus detection. The laboratory-based experimental study design was conducted in Ethiopian Public Health Institute from August to November 2020 on the samples referred to the laboratory for Coronavirus disease-19 testing. Tests were performed on eighty Nasopharyngeal/Oropharyngeal swab samples using the Abbott Real-time severe acute respiratory syndrome coronavirus - 2 assays, a test for the qualitative detection of virus in the sample. Data were analyzed and described by mean and standard deviation. Repeated measurement analysis of variance was used to assess the mean difference between the three temperatures and bulk lysis on viral detection. Post-hock analysis was employed to locate the place of significant differences. P-values less than 0.05 was used to declare statistical significance. About 6.2% (5/80) of samples were changed to negative results in heat inactivation at 60oC and 8.7% (7/80) of samples were changed to negative in heat inactivation at 100oC. The Cyclic threshold values of heat-inactivated samples (at 60oC, at 100oC, and bulk lysis) were significantly different from the temperature at 56oC. The efficacy of heat-inactivation varies greatly depending on temperature and duration. Therefore, local validation and verification of heat-inactivation are essential.