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Introduction: COVID-19 is an acute respiratory tract disease caused by the emerging coronavirus SARS-CoV-2. Although several options for che-moprophylaxis are under development, effective treatment for COVID-19 is not yet available. Objective(s): To investigate the antiviral properties of synthesized silver na-noparticles (AgNPs) against SARS-CoV-2 using in vitro models. Material(s) and Method(s): This work synthesized AgNPs using an electrochemical method and characterized them using physico-chemical techniques (ICP-OES, ultraviolet-visible spectroscopy, and transmission electron microscopy). AgNPs with diameter sizes ranging between 2.6 to 30 nm and an average size of 6.2 nm were obtained by the electrochemical method. The cytotoxic effect and the antiviral activity of prepared AgNPs against SARS-CoV-2 were evaluated in vitro using Vero E6 cells. Cell viability was evaluated by MTT assay in the presence of serial dilutions of AgNPs. The antiviral effect of AgNPs was evaluated before and after the infection of Vero E6 cells by plaque assay. Result(s): Cytotoxic effect was observed at concentrations above 0.07 ppm. AgNPs exhibit a significant reduction of SARS-CoV-2 viral titer after a pre-post treatment strategy with inhibition of 96.5%, 64.13%, and 74.72% at 0.03, 0.017, and 0.008 ppm, respectively. Conclusion(s): Our results suggest that AgNPs could reduce SARS-CoV-2 replication with a low cytotoxic effect. Still, additional in vitro and in vivo studies are required to define its potential therapeutic application in humans. Copyright © 2023 Universidad de Antioquia.
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Introduction. The circulation of SARS-CoV-2 virus variants raises concerns about their potential evasion of the immune response and associated clinical consequences. Decay in the magnitude of the immune response over time after completion of the vaccination schedule has been evidenced. The aim of this study was to evaluate the kinetics of neutralizing antibodies after vaccination and the impact of circulating variants. Materials and methods. Prospective longitudinal study' with a cohort of 60 Colombian adults' who received the complete BNT162b2 vaccine schedule' and were followed for 6 months to determine the kinetics of antibodies. Plaque reduction neutralization assays were performed with live virus' using the B.1 lineage (D614G)' and the Gamma' Alpha' Delta' Mu and Omicron variants of the SARS-CoV-2 virus. Results. Neutralizing capacity against all variants was observed in all individuals after 1 month of vaccination;however' a progressive decrease in neutralizing capacity was observed after 3 and 6 months. Compared to the B.1 lineage' the neutralizing response against the Delta' Mu and Omicron variants presented the greatest decrease' evidencing their immune escape capacity' followed by the Gamma and Alpha variants. The decrease in antibody titers was more evident in men older than 40 years. Conclusions. Despite the safety and effectiveness of the vaccines' it is important to improve and monitor them in order to improve the protective response they can offer.
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Background: Given the current COVID-19 pandemic, numerous drug development studies are being carried out for the treatment and control of this disease. This study aimed to evaluate the in vitro antiviral potential of Corozo fruit extract (Bactris guineensis) against SARS-CoV-2.Methods: Corozo extract (CE) was prepared from the pulp of mature Corozo fruits. The total content of phenols, flavonoids, and anthocyanins in the extracts was determined using the Folin-Ciocalteu, aluminum chloride, and pH differential methods, respectively. The cytotoxicity on Vero E6 cells was evaluated by MTT assay. Antiviral activity was evaluated by pre-post-treatment using a Colombian isolate of SARS-CoV-2. Viral titer was quantified by plaque assay.Results: Anthocyanin concentration of CE was 144.95 +/- 10.3 mg cyanidin-3-glucoside/L. The cytotoxicity of CE on Vero E6 was lower to 20 % at 15.6 g/L. Corozo extract inhibited SARS-CoV-2 at 15.6, 7.8, 3.9 and 1.9 g/L with inhibition percentages of 88.2%, 84%, 59.6% and 56.3%, respectively.Conclusion: This is the first report on the in vitro antiviral effect of Corozo fruit extract against SARS-CoV-2. Since this is a natural product, proven safe for consumption, in the future and with further studies, it could be considered an important functional food that can be useful in preventing strategies to fight against COVID-19.
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Background and Objectives: SARS-CoV-2 variants of concern (VOC) and interest (VOI) pose a significant threat to public health because the rapid change in the SARS-CoV-2 genome can alter viral phenotypes such as virulence, transmissi-bility and the ability to evade the host response. Hence, SARS-CoV-2 quantification techniques are essential for timely diagnosis and follow-up. Besides, they are vital to understanding viral pathogenesis, antiviral evaluation, and vaccine de-velopment. Materials and Methods: Five isolates of SARS-CoV-2: D614G strain (B.1), three VOC (Alpha, Gamma and Delta), and one VOI (Mu) were used to compare three techniques for viral quantification, plaque assay, median tissue culture infectious dose (TCID) and real-time RT-PCR. 50 Results: Plaque assay showed viral titers between 0.15 ± 0.01×107 and 1.95 ± 0.09×107 PFU/mL while viral titer by TCID 50 assay was between 0.71 ± 0.01×106 to 4.94 ± 0.80×106 TCID /mL for the five SARS-CoV-2 isolates. The PFU/mL titer 50 obtained by plaque and the calculated from TCID assays differed by 0.61 log10, 0.59 log10, 0.59 log10 and 0.96 log10 50 for Alfa, Gamma, Delta, and Mu variants (p≤0.0007), respectively. No differences were observed for the D614G strain. Real-time PCR assay exhibited titers ranging from 0.39 ± 0.001×108 to 3.38 ± 0.04×108 RNA copies/µL for all variants. The relation between PFU/mL and RNA copies/mL was 1:29800 for D614G strain, 1:11700 for Alpha, 1:8930 for Gamma, 1:12500 for Delta, and 1:2950 for Mu. Conclusion: TCID assay was comparable to plaque assay for D614G but not for others SARS-CoV-2 variants. Our data 50 demonstrated a correlation among PFU/mL and E gene RNA copies/µL, units of measure commonly used to quantify the viral load in diagnostic and research fields. The results suggest that the proportion of infectious virions in vitro changes de-pending on the SARS-CoV-2 variant, being Mu, the variant reaching a higher viral titer with fewer viral copies.
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Background: Coronavirus infectious disease 2019 (COVID-19) caused by the infection with the new coronavirus SARS-CoV-2 has affected the life and health of more than 222 million people. In the absence of any specific pharmacological treatment, the need to find new therapeutic alternatives is clear. Medicinal plants are widely used worldwide to treat different conditions, including COVID-19;however, in most cases, there are no specific studies to evaluate the efficacy of these treatments. Objective: This article evaluates the antiviral effect of six plant extracts used by indigenous and afro Colombian people against SARS-CoV-2 in vitro. Methods: The antiviral effect of six extracts prepared from plants used in Colombian traditional medicine was evaluated against SARS-CoV-2 through a pre-post treatment strategy on the Vero E6 cell line. Once cytotoxicity was established through an MTT assay, the antiviral effect of the extracts was calculated based on the reduction in the viral titer determined by plaque assay. Results: Gliricidia sepium inhibited SARS-CoV-2 in a 75.6%, 56.8%, 62.5% and 40.0% at 10 mg/mL, 8 mg/mL, 6 mg/mL, and 2 mg/mL, respectively, while Piper tuberculatum treatment reduced viral titer in 33.3% at 6 mg/mL after 48h. Conclusion: G. sepium and P. tuberculatum extracts exhibit antiviral activity against SARS-CoV-2 in vitro.