Comparison of saliva with healthcare workers- and patient-collected swabs in the diagnosis of COVID-19 in a large cohort.

BACKGROUND: A considerable amount of evidence demonstrates the potential of saliva in the diagnosis of COVID-19. Our aim was to determine the sensitivity of saliva versus swabs collected by healthcare workers (HCWs) and patients themselves to assess whether saliva detection can be offered as a cost-effective, risk-free method of SARS-CoV-2 detection. METHODS: This study was conducted in a hospital involving outpatients and hospitalized patients. A total of 3018 outpatients were tested. Of these, 200 qRT-PCR-confirmed SARS-CoV-2-positive patients were recruited for further study. In addition, 101 SARS-CoV-2-positive hospitalized patients with symptoms were also enrolled in the study. From outpatients, HCWs collected nasopharyngeal swabs (NPS), saliva were obtained. From inpatients, HCWs collected swabs, patient-collected swabs, and saliva were obtained. qRT-PCR was performed to detect SARS-CoV-2 by TAQPATH assay to determine the sensitivity of saliva detection. Sensitivity, specificity and positive/negative predictive values (PPV, NPV) of detecting SARS-CoV-2 were calculated using MedCalc. RESULTS: Of 3018 outpatients (asymptomatic: 2683, symptomatic: 335) tested by qRT-PCR, 200 were positive (males: 140, females: 60; aged 37.9 ± 12.8 years; (81 asymptomatic, 119 symptomatic). Of these, saliva was positive in 128 (64%); 39 of 81 asymptomatic (47%),89 of 119 symptomatic patients (74.8%). Sensitivity of detection was 60.9% (55.4-66.3%, CI 95%), with a negative predictive value of 36%(32.9-39.2%, CI 95%).Among 101 hospitalized patients (males:65, females: 36; aged 53.48 ± 15.6 years), with HCW collected NPS as comparator, sensitivity of saliva was 56.1% (47.5-64.5, CI 95%), specificity 63.5%(50.4-75.3, CI95%) with PPV of 77.2% and NPV of 39.6% and that of self-swab was 52.3%(44-60.5%, CI95%), specificity 56.6% (42.3-70.2%, CI95%) with PPV 77.2% and NPV29.7%. Comparison of positivity with the onset of symptoms revealed highest detection in saliva on day 3 after onset of symptoms. Additionally, only saliva was positive in 13 (12.8%) hospitalized patients. CONCLUSION: Saliva which is easier to collect than nasopharyngeal swab is a viable alternate to detect SARS-COV-2 in symptomatic patients in the early stage of onset of symptoms. Although saliva is currently not recommended for screening asymptomatic patients, optimization of collection and uniform timing of sampling might improve the sensitivity enabling its use as a screening tool at community level.

A variant in TMPRSS2 is associated with decreased disease severity in COVID-19.

BACKGROUND: Mortality due to COVID-19 caused by SARS-CoV-2 infection varies among populations. Functional relevance of genetic variations in Angiotensin-converting enzyme 2 (ACE2) and Transmembrane serine protease 2 (TMPRSS2), two crucial host factors for viral entry, might explain some of this variation. METHODS: In this comparative study in Indian subjects, we recruited 510 COVID-19 patients and retrieved DNA from 520 controls from a repository. Associations between variants in ACE2 and TMPRSS2 with disease severity were identified by whole exome sequencing (WES, n = 20) and targeted genotyping (n = 1010). Molecular dynamic simulations (MDS) were performed to explore functional relevance of the variants. Cleavage of spike glycoprotein by wild and variant TMPRSS2 was determined in HEK293T cells. Potential effects of confounders on the association between genotype and disease severity were tested (Mantel-Haenszel test). RESULTS: WES identified deleterious variant in TMPRSS2 (rs12329760, G > A, p. V160M). The minor allele frequency (MAF) was 0·27 in controls, 0·31 in asymptomatic, 0·21 in mild-to-moderately affected and 0·19 in severely affected COVID-19 patients. Risk of severity increased with decreasing MAF: Asymptomatic: Odds ratio-0·69 (95% CI-0·52-0·93; p = 0·01); mild-to-moderate: Odds ratio-1·89 (95% CI-1·22-2.92;p = 0·004) and severe: Odds ratio-1·79 (95% CI-1·11-2.88;p = 0·01). No confounding effect of diabetes and hypertension were observed on the risk of developing severe COVID-19 disease with respect to genotype. MDS revealed decreased stability of TMPRSS2 with 160 M variant. Spike glycoprotein cleavage by TMPRSS2 reduced ~2·4-fold in cells expressing 160 M variant. CONCLUSION: We demonstrate association of TMPRSS2 variant rs12329760 with decreased disease severity in COVID-19 patients from India.

Role of the Gut Microbiome in Nonalcoholic Fatty Liver Disease Progression.

The gut microbiome (GM) is a multifaceted environment wherein nearly 1014 microorganisms play various roles in host immune regulation, intestinal cell proliferation, bone mineralization, xenobiotics metabolism, and protection against pathogens. GM is also strongly coupled with the development and progression of nutrition-related diseases such as nonalcoholic fatty liver disease (NAFLD), wherein the gut-liver axis plays a major role as the gut and liver are functionally and anatomically associated through the portal vein. Dysbiosis causes leaky gut, resulting in the activation of inflammatory processes in the liver. Disruption of the gut barrier enhances microbial infiltration into the sub-mucosae, which through the bloodstream causes harmful microbial metabolites, such as butyrate, long-chain fatty acids, endotoxins, and indole-3-acetic acid, to seep into the liver. In NAFLD patients, these metabolites can lead to the development of nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). In this review, we will discuss the important molecular pathways through which various metabolites and other signaling substances released by the GM regulate liver biology, under both physiological and pathological conditions. Finally, we highlight numerous therapeutic attempts, such as probiotics, prebiotics, and fecal microbial transplantation (FMT), to reprogram the gut-liver axis for decreasing liver diseases.

Genetic variants in TMPRSS2 and Structure of SARS-CoV-2 spike glycoprotein and TMPRSS2 complex

SARS-CoV-2, a highly transmittable pathogen has infected over 3.8 million people around the globe. The spike glycoprotein of SARS-CoV-2 engages host ACE2 for adhesion, TMPRSS2 for activation and entry. With the aid of whole-exome sequencing, we report a variant rs12329760 in TMPRSS2 gene and its mutant V160M, which might impede viral entry. Furthermore, we identified TMPRSS2 cleavage sites in S2 domain of spike glycoprotein and report the structure of TMPRSS2 in complex with spike glycoprotein. We also report the structures of protease inhibitors in complex with TMPRSS2, which could hamper the interaction with spike protein. These findings advance our understanding on the role of TMPRSS2 and in the development of potential therapeutics.Competing Interest StatementThe authors have declared no competing interest.View Full Text