Subject(s)
COVID-19 , SARS-CoV-2 , Humans , RNA, Viral/genetics , SARS-CoV-2/genetics , Tokyo , WastewaterABSTRACT
Genetic testing using reverse transcriptase real-time polymerase chain reaction (rRT-PCR) is the mainstay of diagnosis of COVID-19. However, it has not been fully investigated whether infectious viruses are contained in SARS-CoV-2 genome-positive specimens examined using the rRT-PCR test. In this study, we examined the correlation between the threshold Cycle (Ct) value obtained from the rRT-PCR test and virus isolation in cultured cells, using 533 consecutive clinical specimens of COVID-19 patients. The virus was isolated from specimens with a Ct value of less than 30 cycles, and the lower the Ct value, the more efficient the isolation rate. A cytopathic effect due to herpes simplex virus type 1 contamination was observed in one sample with a Ct value of 35 cycles. In a comparison of VeroE6/TMPRSS2 cells and VeroE6 cells used for virus isolation, VeroE6/TMPRSS2 cells isolated the virus 1.7 times more efficiently than VeroE6 cells. There was no significant difference between the two cells in the mean Ct value of the detectable sample. In conclusion, Lower Ct values in the PCR test were associated with higher virus isolation rates, and VeroE6/TMPRSS2 cells were able to isolate viruses more efficiently than VeroE6 cells.
Subject(s)
COVID-19 , SARS-CoV-2 , Cell Line , Diagnostic Tests, Routine , Humans , Real-Time Polymerase Chain ReactionABSTRACT
In this study, the anti-severe acute respiratory syndrome coronavirus-2 (anti-SARS-CoV-2) activity of mycophenolic acid (MPA) and IMD-0354 was analyzed. These compounds were chosen based on their antiviral activities against other coronaviruses. Because they also inhibit dengue virus (DENV) infection, other anti-DENV compounds/drugs were also assessed. On SARS-CoV-2-infected VeroE6/TMPRSS2 monolayers, both MPA and IMD-0354, but not other anti-DENV compounds/drugs, showed significant anti-SARS-CoV-2 activity. Although MPA reduced the viral RNA level by only approximately 100-fold, its half maximal effective concentration was as low as 0.87 µ m, which is easily achievable at therapeutic doses of mycophenolate mofetil. MPA targets the coronaviral papain-like protease and an in-depth study on its mechanism of action would be useful in the development of novel anti-SARS-CoV-2 drugs.