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1. Dissolvable sugar barriers to enhance the sensitivity of nitrocellulose membrane lateral flow assay for COVID-19 nucleic acid.

Author

Tang R, Alam N, Li M, Xie M, and Ni Y

Subjects
COVID-19 Nucleic Acid Testing instrumentation, DNA chemistry, DNA Probes chemistry, Gold chemistry, Limit of Detection, Metal Nanoparticles chemistry, Polyproteins genetics, SARS-CoV-2 chemistry, Sensitivity and Specificity, COVID-19 Nucleic Acid Testing methods, Collodion chemistry, RNA, Messenger analysis, Sugars chemistry, Viral Proteins genetics
Abstract

Nitrocellulose (NC) membrane can have value-added applications for lateral flow assay (LFA)-based diagnostic tools, which has great potential for the detection of pathogens, such as COVID-19, in different environments. However, poor sensitivity of the NC membrane based LFA limits its further application in many cases. Herein, we developed a facile method for LFA sensitivity enhancement, by incorporating two-sugar barrier into LFAs: one between the conjugation pad and the test line, and the other between the test line and the control line. ORF1ab nucleic acid of COVID-19 was used as the model target to demonstrate the concept on the HF120 membrane. Results show that at optimum conditions, the two sugar barrier LFAs have a detection limit of 0.5 nM, which is compared to that of 2.5 nM for the control LFA, achieving a 5-fold sensitivity increase. This low cost, easy-to-fabricate and easy-to-integrate LFA method may have potential applications in other cellulose paper-based platforms., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Published
2021
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2. Direct activation of caspase 8 by the proapoptotic E2 protein of HPV18 independent of adaptor proteins

Author

Caroline Demeret, Françoise Thierry, Expression Génétique et Maladies (EGM), Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), This work was supported by the Pasteur Institute, CNRS, Association pour la Recherche sur le Cancer (ARC) and La Ligue Contre le Cancer., We thank Moshe Yaniv and Jonathan Weitzman for critical reading of the paper. We thank Richard Siegel, Marcus Peter, Visha Dixit and Richard Kitsis for providing expression plasmids., and Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cytoplasm, Death fold, Fas-Associated Death Domain Protein, Caspase 2, Caspase 3, Apoptosis, Biology, Caspase 8, Protein Structure, Secondary, Cell Line, 03 medical and health sciences, Viral Proteins, Humans, FADD, Molecular Biology, 030304 developmental biology, 0303 health sciences, NLRP1, 030302 biochemistry & molecular biology, Cell Biology, Oncogene Proteins, Viral, Cell biology, Enzyme Activation, Death-inducing signaling complex, [SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology, biology.protein, Caspase 10
Abstract

International audience; The self-activation of initiator caspases is dependent on their oligomerization driven by interaction with the death fold domains (DFD) of adaptor proteins. Here, we show that the E2 protein of human papillomavirus type 18 triggers apoptosis by assembling cytoplasmic filaments together with caspase 8, in which its efficient self-activation occurs. The E2 protein binds directly to the death effector domains (DED) of caspase 8 through non-DFD interaction. This interaction is independent of FADD, but it can cooperate with FADD homotypic binding to caspase 8 to induce its oligomerization; hence cell death, while it is antagonized by competitive binding of MC159 FLICE inhibitory protein. The amino-terminal domain of E2 contains a 27 amino-acid a-helix, which is necessary and sufficient to induce caspase oligomerization and cell death. Our results provide evidence for adaptor-independent oligomerization of caspase 8, mediated by non-DFD direct interactions with the HPV18 E2 protein, thus deciphering a new pathway for caspase 8 activation.

Published
2008