• Endogenous Biomarkers Analysis and False-Negative Results for SARSCov2 Using two Commercial RT-PCR Diagnostic Kits
  • Mahdieh Khoshakhlagh,1,*
    1. Department of Biochemistry, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran


  • Introduction: Real-time PCR is a commonly employed method for identifying SARS-CoV-2, the virus accountable for COVID-19. However, it is possible to encounter inaccurate negative outcomes despite the inclusion of internal controls. This research aimed to explore how utilizing different internal control substances affects the precision of SARS-CoV-2 detection kits.
  • Methods: During the period spanning December 2021 to January 2022, a total of 162 respiratory tract samples were gathered from individuals exhibiting symptoms suggestive of COVID-19 at Ghaem Hospital in Mashhad, IR Iran. These samples underwent an initial screening utilizing the Pishtaz Teb kit, featuring a DNA-based internal control. Subsequently, those samples yielding negative results were subjected to a secondary examination using the Geneova kit, which incorporates an RNA-based internal control. Throughout this process, both positive and negative controls were consistently employed to ensure the accuracy and reliability of the outcomes.
  • Results: Following the retesting using the Geneova kit, only one patient among the 162 negative samples tested positive for SARS-CoV-2. Both the Pishtaz Teb and Geneova controls consistently yielded the anticipated results. However, it's worth noting that the Geneova internal control aligned with the Pishtaz Teb control in only 44% of instances. This discrepancy may be attributed to a higher threshold cycle value for the Geneova internal control, implying potential RNA degradation during the course of the experiment.
  • Conclusion: Effective quality control procedures, which encompass the utilization of suitable internal control materials, play a pivotal role in ensuring precise SARS-CoV-2 detection. This study underscores the significance of opting for dependable diagnostic kits characterized by exceptional sensitivity and specificity, as this choice can substantially mitigate the occurrence of false-negative outcomes, especially in scenarios involving a limited viral presence or the early phases of the disease. The incorporation of an RNA internal control serves the purpose of detecting RNA degradation, thereby aiding in the identification of potential false-negative diagnoses. This, in turn, contributes to enhanced disease control and management. Further research is needed to enhance the accuracy of COVID-19 diagnostic tests.
  • Keywords: COVID-19, Real-time PCR, internal control, false-negative diagnoses, respiratory tract samples