Objectives: The purpose of the current study was to evaluate the analytical performance of seven kits for detecting IgM/IgG antibodies against coronavirus (SARS-CoV-2) by using four chemiluminescence immunoassay systems. Methods: Fifty patients diagnosed with SARS-CoV-2 infection and 130 controls without coronavirus infection from the General Hospital of Chongqing were enrolled in the current retrospective study. Four chemiluminescence immunoassay systems, including seven IgM/IgG antibody detection kits for SARS-CoV-2 (A_IgM, A_IgG, B_IgM, B_IgG, C_IgM, C_IgG, and D_Ab), were employed to detect antibody concentrations. The chi-square test, the receiver operating characteristic (ROC) curve and Youdenâs index were determined to verify the cutoff value of each detection system. Results: The repeatability verification results of the A, B, C, and D systems are all qualified. D-Ab performed best (92% sensitivity and 99.23% specificity), and B_IgM performed worse than the other systems. Except for the A_IgM and C_IgG systems, the optimal diagnostic thresholds and cutoff values of the other kits and their recommendations are inconsistent with each other. B_IgM had the worst AUC, and C_IgG had the best diagnostic accuracy. More importantly, the B_IgG system had the highest false positive rate for testing patients with AIDS, tumours and pregnancies. The A_IgM system test showed the highest false positive rates among elderly individuals over 90 years old. COVID-2019 IgM/IgG antibody test systems exhibit performance differences. Conclusions: The D-Ab serum diagnosis kit is the most reliable detection system for anti-SARS-CoV-2 antibodies, which can be used as an alternative method for nucleic acid testing.
The quick spread of nosocomial bacterial infections and the increasing prevalence of drugresistant strains make the development of novel drugs for pathogens an urgent priority. Quorum sensing (QS) is a communication mechanism used by bacteria to recognize population density fluctuations and control gene expression, which play a critical role both in intraspecies and interspecies communications and regulates microbe-host interactions. Low-molecular-weight signal compounds, such as acyl-homoserine lactone and autoinducing peptide, are used by QS to control the expression of different pathogenic factors. Thus QS--and QS signal molecules in particular--is an attractive target for developing novel antimicrobial methods. Quorum-quenching enzymes, which hydrolyze or modify signal molecules in QS circuit systems to inhibit the expression of bacteria virulence factors, have been identified both in prokaryotes and eukaryotes. Understanding the mechanism of action of quorum-quenching enzymes also provides a promising means to control bacterial infection. This review first introduces the novel principle underling signal-based QS systems in several important pathogens and then focuses on the newly identified quorum-quenching enzymes, including lactonases, acylases, oxidoreductases, and paraoxonases; this summary introduces new concepts of antimicrobial infection.
BackgroundThe purpose of current study is to evaluate the analytical performance of seven kits for detecting IgM/IgG antibody of corona virus (2019-nCoV) by using four chemiluminescence immunoassay systems.
Methods50 patients diagnosed with 2019-nCoV infection and 130 controls without corona virus infection from the General Hospital of Chongqing were enrolled in current retrospective study. Four chemiluminescence immunoassay systems including seven IgM/IgG antibody detection Kits for 2019-nCoV (A_IgM, A_IgG, B_IgM, B_IgG, C_IgM, C_IgG, D_Ab) were employed to detecting antibody concentration.Chi-square test, receiver operating characteristic (ROC) curve and Youden's index were demonstrated to verify the cutoff value of each detection system.
ResultsThe repeatability verification results of the A, B, C, and D system are all qualified. D-Ab performances best (92% sensitivity and 99.23% specificity), and B_IgM worse than other systems. Except for the system of A_IgM and C_IgG, the optimal diagnostic thresholds and cutoff value of other kits from recommendations are inconsistent with each other. B_IgM got the worst AUC and C_IgG had the best diagnostic accuracy. More importantly, B_IgG system have the highest false positive All rights reserved. No reuse allowed without permission. : medRxiv preprint 2 rate for testing patients with AIDS, tumor and pregnant. A_IgM system test showed highest false positive rates among elder over 90 years old.
ConclusionsSystems for CoVID-2019 IgM/IgG antibody test performance difference. Serum diagnosis kit of D-Ab is the most reliable detecting system for 2019-nCoV antibody, which can be used as an alternative method for nucleic acid testing.
In this work, we constructed a novel electrochemiluminescent (ECL) strategy based on sandwich immunoassay-induced target transformation assisted with catalyzed hairpin assembly (CHA) amplification for ultrasensitive bioassay with cysteine-rich protein 61 (CCN1) as a model. First, the target CCN1 could be equally transformed into the specific oligonucleotide (initiator I) labeled on the detection antibody based on the specific sandwich immunoassay. In addition, the initiator I triggered an efficient nonenzymatic CHA amplification in the presence of ferrocene-labeled hairpin 1 (Fc-H1) and hairpin 2 (H2) to produce massive hybrids (Fc-H1−H2) containing a sticky end labeled with ferrocene. Finally, Fc-H1−H2 could be immobilized on the capture probe single-stranded DNA (ssDNA)-modified electrode through the hybridization between the sticky end of Fc-H1−H2 and ssDNA, and a significantly quenched ECL signal could be obtained due to the efficient quench effect between ferrocene and the ECL indicator, ruthenium(II) tris(4,4′-dicarboxylicacid-2,2′-bipyridyl) [Ru(dcbpy) 3 2+ ], immobilized on the surface of the electrode, which was related to the concentration of target CCN1. As expected, the proposed ECL biosensor exhibited a relatively low detection limit of 3.9 fg/mL in a linear range from 10 fg/mL to 100 ng/mL. This ECL strategy inspired the clinical examination of the biomarker CCN1, providing potential application in early diagnosis and malignant monitoring of cancer.
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