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The ongoing COVID-19 pandemic has caused millions of deaths and the continued emergence of new variants suggests continued circulation in the human population. In the current time of vaccine availability and new therapeutic development, including antibody-based therapies, many questions about long-term immunity and protection remain uncertain. Identification of protective antibodies in individuals is often done using highly specialized and challenging assays such as functional neutralizing assays, which are not available in the clinical setting. Therefore, there is a great need for the development of rapid, clinically available assays that correlate with neutralizing antibody assays to identify individuals who may benefit from additional vaccination or specific COVID-19 therapies. In this report, we apply a novel semi-quantitative method to an established lateral flow assay (sqLFA) and analyze its ability to detect the presence functional neutralizing antibodies from the serum of COVID-19 recovered individuals. We found that the sqLFA has a strong positive correlation with neutralizing antibody levels. At lower assay cutoffs, the sqLFA is a highly sensitive assay to identify the presence of a range of neutralizing antibody levels. At higher cutoffs, it can detect higher levels of neutralizing antibody with high specificity. This sqLFA can be used both as a screening tool to identify individuals with any level of neutralizing antibody to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or as a more specific tool to identify those with high neutralizing antibody levels who may not benefit from antibody-based therapies or further vaccination.
RESUMEN
Background: SARS-CoV-2 antigen-based tests are well-calibrated to infectiousness and have a critical role to play in the COVID-19 public health response. We report the development and performance of a unique lateral flow immunoassay (LFA). Methods: Combinations of several monoclonal antibodies targeting multiple antigenic sites on the SARS-CoV-2 nucleocapsid protein (NP) were isolated, evaluated, and chosen for the development of a LFA termed CoV-SCAN (BioMedomics, Inc.). Clinical point-of-care studies in symptomatic and asymptomatic individuals were conducted to evaluate positive predictive agreement (PPA) and negative predictive agreement (NPA) with RT-PCR as comparator. Results: In laboratory testing, CoV-SCAN detected 14 recombinant N-proteins of SARS-CoV-2 variants with sensitivity in the range of 0.2-3.2 ng/mL, and 10 authentic SARS-CoV-2 variants with sensitivity in the range of 1.6-12.5 TCID50/swab. No cross reactivity was observed with other human coronaviruses or other respiratory pathogens. In clinical point-of-care testing on 148 individuals over age 2 with symptoms of ≤5 days, PPA was 87.2% (CI 95: 78.3-94.8%) and NPA was 100% (CI 95: 94.2-100%). In another 884 asymptomatic individuals, PPA was 85.7% (CI 95: 42.1-99.6%) and 99.7% (99.0-99.9%). Overall, CoV-SCAN detected over 97.2% of specimens with CT values <30 and 93.8% of nasal swab specimens with the Omicron variant, even within the first 2 days after symptom onset. Conclusions: The unique construction of CoV-SCAN using two pairs of monoclonal antibodies has resulted in a test with high performance that remains durable across multiple variants in both laboratory and clinical evaluations. CoV-SCAN should identify almost all individuals harboring infectious SARS-CoV-2. Summary: Unique construction of a point-of-care rapid antigen test using two pairs of monoclonal antibodies has led to good performance that remained durable across multiple variants in laboratory and clinical evaluations. Test should identify almost all individuals harboring infectious SARS-CoV-2.
RESUMEN
BACKGROUND: Neutrophil extracellular traps (NETs) are involved in the development of sepsis-induced acute respiratory distress syndrome (ARDS). Glycyrrhizin (GL), the main active ingredient of the traditional Chinese medicine Glycyrrhiza glabra, has anti-inflammatory, anti-viral, and immunomodulatory effects. OBJECTIVE: The study aims to explore the efficacy and potential mechanism of GL on sepsis-induced ARDS in mice. MATERIALS AND METHODS: Mice were randomly divided into 3 groups: Control, CLP, and GL + CLP. Mice sepsis ARDS model was induced by cecal ligation and puncture (CLP) followed by intraperitoneal GL treatment. Then, the 7-day survival rate of mice was recorded. The lung function of mice was determined by whole-body plethysmography. Lung pathology and scores were observed by hematoxylin-eosin staining. The wet/dry ratio (W/D) of the lung was measured by weighing method. The protein concentration in bronchoalveolar lavage fluid (BALF) was measured by the BCA method. NETs formation in lung tissue was detected by immunofluorescence. Furthermore, HMGB1ãTLR9ãMyD88 and IL6 expression in lung tissue were detected by western blot and by quantitative real-time PCR, respectively. RESULTS: The results showed that GL improved the survival rate, attenuated lung tissue injury and reduced the expression of inflammatory factors in mice with CLP-induced sepsis. Meanwhile, we confirmed that GL could inhibit TLR9 / MyD88 activation from reducing NETs formation by decreasing HMGB1 expression. The formation of NETs is regulated by HMGB1 / TLR9 / MyD88. In addition, GL improved lung function in mice with sepsis-induced ARDS. Lung function suggested that GL increased alveolar ventilation, alleviated ventilator fatigue and reduced airway resistance in mice with ARDS induced by sepsis. CONCLUSIONS: GL ameliorated sepsis-induced ARDS and reduced the NETs formation in lung tissues, which may be associated with the inhibition of the HMGB1 / TLR9 pathway.
