Quantitative Assay of SARS-CoV-2 RNA and Level of Proinflammatory Protein Gene Transcripts in Peripheral Blood Leukocytes after a Novel Coronavirus Infection

The possibility of finding persistent SARS-CoV-2 viral particles in human peripheral blood leukocytes after a novel coronavirus infection was shown. The results of droplet digital PCR showed that 19 of 24 examined subjects had from 4 to 555 copies of the Nsp4 SARS-CoV-2 gene in 5-6 months after infection. The presence of this transcript in peripheral blood leukocytes was associated with reduced expression of FOXP3 gene and increased level of RORγ gene mRNA. The copy number of the Nsp4 gene negatively correlated with the level of FOXP3 gene mRNA (r=-0.45; p=0.028), but showed a positive correlation with the DANCR long non-coding RNA (r=0.94; p<0.001). In SARS-CoV-2-positive healthy individuals, the level of TLR2, NLRP3, and IL1B gene transcripts was higher than in SARS-CoV-2-negative donors. The presence of SARS-CoV-2 in a persistent form is probably associated with impaired immunosuppression and the development of chronic inflammation in apparently healthy volunteers after a new coronavirus infection.