Detection of SARS-CoV-2 in Different Human Biofluids Using the Loop-Mediated Isothermal Amplification Assay: A Prospective Diagnostic Study in Fortaleza, Brazil

We adopted the reverse transcriptase - loop mediated isothermal amplification (RT-LAMP) to detect SARS-Cov-2 in patient samples. Two primer sets for genes N and Orf1ab were designed to detect SARS-CoV-2, and one primer set was designed to detect the human gene Actin. We collected prospective 138 nasopharyngeal swabs, 70 oropharyngeal swabs, 69 saliva, and 68 mouth saline wash samples from patients suspected to have severe acute respiratory syndrome (SARS) caused by SARS-CoV-2 to test the RT-LAMP in comparison with the golden standard technique RT-qPCR. Accuracy of diagnosis using both primers, N5 and Orf9, was evaluated. Sensitivity and specificity for diagnosis was 96% (95% CI 87-99) and 85% (95% CI 76-91) in 138 samples, respectively. Accurate diagnosis results were obtained only in nasopharyngeal swab processed via extraction kit. Accurate and rapid diagnosis could aid COVID-19 pandemic management by identifying, isolating, and treating patients rapidly. HighlightsO_LINew nucleic acid amplification test for the diagnosis of SARS-CoV-2 using the RT-LAMP C_LIO_LIN5 primer set showed mutations in strains of interest, such as the gamma strain (P.1) of SARS-CoV-2 C_LIO_LIWhen evaluated in combination N5 and Orf9 primer sets maintained high sensitivity and specificity C_LI

Clinical Trial of Efficacy and Toxicity of Disoproxil Tenofovir Fumarate and Emtricitabine for Mild to Moderate SARS-CoV-2 Infections

This study aimed to evaluate the efficacy and toxicity of tenofovir (TDF) and TDF combined with emtricitabine (TDF/FTC) in patients with mild to moderate COVID-19 infections. We conducted a randomized, double-blind, placebo-controlled clinical trial in patients with clinical suspicion of mild to moderate respiratory infection caused by SARS-CoV-2 who were treated at an outpatient clinic. Patients were randomly recruited to take 10 days of TDF (300 mg/day), TDF (300 mg/day) combined with FTC (200 mg/day) or placebo Vitamin C (500 mg/day). The primary parameter was the score of symptoms and predictive signs of COVID-19, assessed on the seventh day of patient follow-up. From a total of 309 patients with clinical suspicion of SARS-CoV-2, 227 met the inclusion criteria and were randomly distributed into the following groups: (a) 75 (one did not initiate treatment) in the TDF group; (b) 74 in the TDF combined with FTC group; and (c) 77 in the Vitamin C group (placebo). Of the 226 patients, 139 (62%) were positive for SARS-CoV-2. Fever ([≥]37.8{degrees}C), ageusia or dysgeusia, anosmia or dysosmia, and two or more clinical symptoms or signs were significantly associated with SARS-CoV-2 infection. There was no significant change in clinical score based on clinical symptoms and signs between treatment groups. Patients with mild to moderate infection by SARS-CoV-2 had higher concentrations of G-CSF, IL-1{beta}, IL-6 and TNF- compared to patients without infection. Patients with mild to moderate respiratory infection, with fever ([≥]37.8{degrees}C), loss of smell, loss of taste and two or more symptoms, have a better prediction for the diagnosis of COVID-19. Patients with SARS-CoV-2 showed higher and more persistent proinflammatory cytokines profile compared to patients not infected with SARS-CoV-2. Pharmacological intervention with TDF or TDF combined with FTC did not change the clinical signs and symptoms score in mild to moderate respiratory infection in patients with SARS-CoV-2 compared to the Vitamin C group (placebo).

Evaluation of 16S rRNA qPCR for detection of Mycobacterium leprae DNA in nasal secretion and skin biopsy samples from multibacillary and paucibacillary leprosy cases.

Mycobacterium leprae bacilli are mainly transmitted by the dissemination of nasal aerosols from multibacillary (MB) patients to susceptible individuals through inhalation. The upper respiratory tract represents the main entry and exit routes of M. leprae. Therefore, this study aimed to evaluate the sensitivity and specificity of real-time quantitative polymerase chain reaction (qPCR) in detecting M. leprae in nasal secretion (NS) and skin biopsy (SB) samples from MB and paucibacillary (PB) cases. Fifty-four NS samples were obtained from leprosy patients at the Dona Libânia National Reference Centre for Sanitary Dermatology in Ceará, Brazil. Among them, 19 MB cases provided both NS and SB samples. Bacilloscopy index assays were conducted and qPCR amplification was performed using specific primers for M. leprae 16S rRNA gene, generating a 124-bp fragment. Primer specificity was verified by determining the amplicon melting temperature (Tm = 79.5 °C) and detection limit of qPCR was 20 fg of M. leprae DNA. Results were positive for 89.7 and 73.3% of NS samples from MB and PB cases, respectively. SB samples from MB patients were 100% positive. The number of bacilli detected in NS samples were 1.39 × 103-8.02 × 105, and in SB samples from MB patients were 1.87 × 103-1.50 × 106. Therefore, qPCR assays using SYBR Green targeting M. leprae 16S rRNA region can be employed in detecting M. leprae in nasal swabs from leprosy patients, validating this method for epidemiological studies aiming to identify healthy carriers among household contacts or within populations of an endemic area.

Bothrops leucurus venom induces nephrotoxicity in the isolated perfused kidney and cultured renal tubular epithelia.

Bites from snake (Bothrops genus) cause local tissue damage and systemic complications, which include alterations such as hemostatic system and acute renal failure (ARF). Recent studies suggest that ARF pathogenesis in snakebite envenomation is multifactorial and involves hemodynamic disturbances, immunologic reactions and direct nephrotoxicity. The aim of the work was to investigate the effects of the Bothrops leucurus venom (BlV) in the renal perfusion system and in cultured renal tubular cells of the type MDCK (Madin-Darby Canine kidney). BlV (10 µg/mL) reduced the perfusion pressure at 90 and 120 min. The renal vascular resistance (RVR) decreased at 120 min of perfusion. The effect on urinary flow (UF) and glomerular filtration rate (GFR) started 30 min after BlV infusion, was transient and returned to normal at 120 min of perfusion. It was also observed a decrease on percentual tubular transport of sodium (%TNa(+)) at 120 min and of chloride (%TCl(-)) at 60 and 90 min. The treatment with BlV caused decrease in cell viability to the lowest concentration tested with an IC(50) of 1.25 µg/mL. Flow cytometry with annexin V and propidium iodide showed that cell death occurred predominantly by necrosis. However, a cell death process may involve apoptosis in lower concentrations. BlV treatment (1.25 µg/mL) led to significant depolarization of the mitochondrial membrane potential and, indeed, we found an increase in the expression of cell death genes in the lower concentrations tested. The venom also evoked an increase in the cytosolic Ca(2+) in a concentration dependent manner, indicating that Ca(2+) may participate in the venom of B. leucurus effect. The characterization of the effects in the isolated kidney and renal tubular cells gives strong evidences that the acute renal failure induced by this venom is a result of the direct nephrotoxicity which may involve the cell death mechanism.