Detection of the SARS-CoV-2 Genome in Peripheral Blood Mononuclear Cells of Hospitalized Patients With COVID-19 Infection

Background: Evaluation of viral pathogenicity is an important part of research in every viral disease, and one of the most important parts of pathogenicity is cell and tissue tropism of viruses, which can help us to have a clear picture of the viral replication cycle and viral disease. Objectives: This study aims to evaluate the possibility of SARS-CoV-2 replication in peripheral blood mononuclear cells (PBMCs) of hospitalized patients with COVID-19. Methods: Twenty-six whole blood samples (5 mL) were collected from 70 hospitalized patients infected with SARS-CoV-2. Plasma and PBMCs were collected and subjected to total RNA extraction using the alcohol-chloroform precipitation method by the RNX solution. After complementary DNA (cDNA) synthesis, all samples were subjected to real-time and nested polymerase chain reactions (PCRs) to detect the viral genome. Results: The nested PCR method showed a higher rate of positivity in plasma samples (42.3%) compared to real-time PCR (30.7%), suggesting nested PCR exhibited better sensitivity. This rate in PBMC samples was 57.7% by nested PCR and 7.7% by real-time PCR. Minus-strand viral genome was detected in PBMCs, demonstrating that these cells can support virus replication and act as a virus transporter through blood. Conclusions: PBMCs can be infected with SARS-CoV-2. Plasma and serum samples are also not useful samples for virus detection because all of the positive plasma samples in this study showed low viral load with a low cycle threshold (Ct) value.