Comparison of Real-time RT-PCR cycle threshold (Ct) values with clinical features and severity of COVID-19 disease among hospitalized patients in the first and second waves of COVID-19 pandemic in Chennai, India.

Introduction: Real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) of nasopharyngeal/ oropharyngeal swab has been the gold standard test for detection of SARS-CoV-2 infection The relationship between cycle threshold (Ct) values of rRT-PCR and severity of disease remain disputable and not clearly defined in COVID-19. Methodology: This is a single-centered retrospective observational study conducted at Government Corona Hospital (GCH), Guindy, Chennai. In the present study, we compared the Ct value of rRT-PCR from nasopharyngeal swab specimens with a diverse range of symptoms and disease severity among 240 individuals who were hospitalized with COVID-19, viz., mild cases (MC; n = 160), moderately severe cases (MSC; n = 46) and severe cases (SC; n = 34) in the first and second waves of COVID-19 pandemic. Results: The study included 240 hospitalized COVID-19 patients with a median age of 52 years (range 21 to 90 years). MC, MSC, and SC all had median Ct values of 25.0 (interquartile range - IQR 20.0 to 30.5), 29.5 (IQR 23.0 to 34.0), and 29.0 (IQR 24 to 37.5) for the ORF1ab gene. The Ct value differed significantly between mild vs moderate, and mild vs severe cases. The Ct value of SC group with co-morbidity of type 2 diabetes have a significant difference compared to non-diabetes group (p value <0.05). There was a significant difference in the median Ct value of ORF1ab gene among the MSC group and MC but not in the SC group in the first and second waves of the pandemic (p<0.05). Conclusion: We conclude that SARS-CoV-2 Ct values of rRT-PCR alone does not have a role in aiding severity stratification among patients with COVID-19 since the viral dynamics and Ct value may vary due to the emerging variants that occur in different waves of the pandemic.

Mitogen-activated protein kinases mediate the production of B-cell lymphoma 2 protein by Mycobacterium tuberculosis in monocytes.

Changes in the levels of antiapoptotic protein B-cell lymphoma 2 (Bcl-2) protein has been reported in murine and human tuberculosis. We investigated the role of mitogen-activated protein kinase pathways in the production of Bcl-2 protein in THP-1 human monocytes infected with Mycobacterium tuberculosis H37Rv and H37Ra. Analysis of phosphorylation profiles of mitogen-activated protein kinase kinase-1, extracellular-signal regulated kinase 1/2, mitogen-activated protein kinase kinase 3/6, and p38 mitogen-activated protein kinase; B-cell lymphoma 2 kinetics; and tumor necrosis factor-α (TNF-α) secretion levels showed variation between the two strains. Mycobacterium tuberculosis H37Rv induced higher Bcl-2 and lower TNF-α levels, whereas H37Ra the reverse. The strains also differed in their usage of CD14 and human leukocyte antigen-DR receptors in mediating extracellular-signal regulated kinase 1/2 and p38 mitogen-activated protein kinase activation. Mycobacterium tuberculosis H37Rv- and H37Ra-induced Bcl-2 production was reduced by specific inhibitors of mitogen-activated protein kinase kinase-1 (PD98059) and p38 (SB203580), but increased by nuclear factor κB (NF-κB) inhibitor (BAY 11-7082). TNF-α production by both strains was reduced in the presence of specific inhibitors of mitogen-activated protein kinase kinase-1 (PD98059), p38 (SB203580), and NF-κB (BAY 11-7082). Furthermore, inhibition of NF-κB was accompanied by an increase in strain-induced extracellular-signal regulated kinase 1/2 phosphorylation. Collectively, these results indicate for the first time that the production of Bcl-2 and TNF-α by M. tuberculosis H37Rv/H37Ra-infected THP-1 human monocytes is mediated through mitogen-activated protein kinases and NF-κB.