EVALUATION OF THE STABILITY OF RNA SARS-CoV-2 IN MULTIPLE FREZEE-THAW CYCLES USING REAL-TIME PCR METHOD

Introduction/ Objectives: According to WHO, clinical samples collected in retrospective clinical studies are required to provide stability claims for each storage condition, such as duration at different temperatures and freeze/thaw cycles[1]. This study was conducted to evaluate the effects of multiple freeze/thaw (FT) cycles on the concentration of RNA SARS-CoV-2 (extracted from retrospective clinical sample) by using Real-time PCR method. Methods: Descriptive laboratory study. We used a commercial Real-time PCR assay and reference standard for quantification of RNA concentration after each FT cycle. Results: We observed that the extracted RNA SARS-CoV-2 remained stable and did not show significantly different Ct values (equivalent to viral loads) over 10 FT cycles (p >0.05), compared to those Ct values at time point 0. Variations of Ct values over 10 FT cycles ranged from 0.64% to 1.64%. The mean difference in viral load was 0,12log10IU/ml. Conclusions: Our study results proved that RNA SARS-CoV-2 extracted from clinical samples can remain stable over 10 freeze-thaw cycles and can be used as a evaluation panel for quality control of in vitro diagnostic test kits detecting SARS-CoV-2.