Effectiveness and policies analysis of pool testing method for COVID-19

Purpose: This research aims to figure out whether the pool testing method of SARS-CoV-2 for COVID-19 is effective and the optimal sample size is in one bunch. Additionally, since the infection rate was unknown at the beginning, this research aims to propose a multiple sampling approach that enables the pool testing method to be utilized successfully. Design/methodology/approach: The authors verify that the pool testing method of SARS-CoV-2 for COVID-19 is effective under the situation of the shortage of nucleic acid detection kits based on probabilistic modeling. In this method, the testing is performed on several samples of the cases together as a bunch. If the test result of the bunch is negative, then it is shown that none of the cases in the bunch has been infected with the novel coronavirus. On the contrary, if the test result of the bunch is positive, then the samples are tested one by one to confirm which cases are infected. Findings: If the infection rate is extremely low, while the same number of detection kits is used, the expected number of cases that can be tested by the pool testing method is far more than that by the one-by-one testing method. The pool testing method is effective only when the infection rate is less than 0.3078. The higher the infection rate, the smaller the optimal sample size in one bunch. If N samples are tested by the pool testing method, while the sample size in one bunch is G, the number of detection kits required is in the interval (N/G, N). Originality/value: This research proves that the pool testing method is not only suitable for the situation of the shortage of detection kits but also the situation of the overall or sampling detection for a large population. More importantly, it calculates the optimal sample size in one bunch corresponding to different infection rates. Additionally, a multiple sampling approach is proposed. In this approach, the whole testing process is divided into several rounds in which the sample sizes in one bunch are different. The actual infection rate is estimated gradually precisely by sampling inspection in each round. © 2021, Emerald Publishing Limited.

Two-Helix Supramolecular Proteomimetic Binders Assembled via PNA-Assisted Disulfide Crosslinking.

Peptidic motifs folded in a defined conformation are able to inhibit protein-protein interactions (PPIs) covering large interfaces and as such they are biomedical molecules of interest. Mimicry of such natural structures with synthetically tractable constructs often requires complex scaffolding and extensive optimization to preserve the fidelity of binding to the target. Here, we present a novel proteomimetic strategy based on a 2-helix binding motif that is brought together by hybridization of peptide nucleic acids (PNA) and stabilized by a rationally positioned intermolecular disulfide crosslink. Using a solid phase synthesis approach (SPPS), the building blocks are easily accessible and such supramolecular peptide-PNA helical hybrids could be further coiled using precise templated chemistry. The elaboration of the structural design afforded high affinity SARS CoV-2 RBD (receptor binding domain) binders without interference with the underlying peptide sequence, creating a basis for a new architecture of supramolecular proteomimetics.

CRISPR/Cas12a-Enabled Multiplex Biosensing Strategy Via an Affordable and Visual Nylon Membrane Readout.

Most multiplex nucleic acids detection methods require numerous reagents and high-priced instruments. The emerging clustered regularly interspaced short palindromic repeats (CRISPR)/Cas has been regarded as a promising point-of-care (POC) strategy for nucleic acids detection. However, how to achieve CRISPR/Cas multiplex biosensing remains a challenge. Here, an affordable means termed CRISPR-RDB (CRISPR-based reverse dot blot) for multiplex target detection in parallel, which possesses the advantages of high sensitivity and specificity, cost-effectiveness, instrument-free, ease to use, and visualization is reported. CRISPR-RDB integrates the trans-cleavage activity of CRISPR-Cas12a with a commercial RDB technique. It utilizes different Cas12a-crRNA complexes to separately identify multiple targets in one sample and converts targeted information into colorimetric signals on a piece of accessible nylon membrane that attaches corresponding specific-oligonucleotide probes. It has demonstrated that the versatility of CRISPR-RDB by constructing a four-channel system to simultaneously detect influenza A, influenza B, respiratory syncytial virus, and SARS-CoV-2. With a simple modification of crRNAs, the CRISPR-RDB can be modified to detect human papillomavirus, saving two-thirds of the time compared to a commercial PCR-RDB kit. Further, a user-friendly microchip system for convenient use, as well as a smartphone app for signal interpretation, is engineered. CRISPR-RDB represents a desirable option for multiplexed biosensing and on-site diagnosis.

Risk preference, risk perception, and purchase recovery period: Empirical evidence from salmon contamination of COVID-19 in China

This paper investigates the recovery period of consumer salmon purchase intention after food scares at the Xinfadi wholesale market in China during the COVID-19 pandemic and examines the impact mechanism of risk preference and risk perception on the period duration. Our empirical analysis is based on a survey of 655 salmon consumers in Beijing, Tianjin, and Shanghai. We estimate that the purchase intention recovery period lasts 21 weeks among the surveyed consumers after the shock. Although the epidemic risk levels of the three cities are different, there is a significant difference only in the recovery period from 5 to 7th weeks. The Cox proportional hazards model results further show that consumers with less risk-averse are more active in resuming purchase intention, and the effect of risk perception is just the opposite. Moreover, risk perception has a moderating effect on risk preference and recovery period. Finally, we put forward three possible policy implications: attaching nucleic acid detection certificate, strengthening cold chain management, and diversifying cooking methods.

Design and Optimize of Campus Nucleic Acid Tests Queuing System

Covid-19 is more likely to spread in campus than it in other places because students live together without masks. In this case, it is necessary to take nucleic acid tests in a unified time regularly. To make nucleic acid tests efficient and convenient to manage students and the testing time, this article would apply queuing theory to design a nucleic acid tests queuing system by using the data from Sanda University in April 2022. According to the special conditions on campus, such as course schedule, students' daily activities, and campus management, students would be grouped by several management styles. The system would calculate the start time and waiting time for each group and would strive to take nucleic acid tests in an orderly manner with minimal waiting time. © 2022 IEEE.

Automated sample-to-answer system for rapid and accurate diagnosis of emerging infectious diseases

Automated sample-to-answer systems that promptly diagnose emerging infectious diseases, such as zoonotic diseases, are crucial to preventing the spread of infectious diseases and future global pandemics. However, automated, rapid, and sensitive diagnostic testing without professionals and sample capacity and type limitations remains unmet needs. Here, we developed an automated sample-to-answer diagnostic system for rapid and accurate detection of emerging infectious diseases from clinical specimens. This integrated system consists of a microfluidic platform for sample preparation and a bio-optical sensor for nucleic acid (NA) amplification/detection. The microfluidic platform concentrates pathogens and NAs in a large sample volume using adipic acid dihydrazide and a low-cost disposable chip. The bio-optical sensor allows label-free, isothermal one-step NA amplification/detection using a ball-lensed optical fiber-based silicon micro-ring resonator sensor. The system is integrated with software to automate testing and perform analysis rapidly and simply;it can distinguish infection status within 80 min. The detection limit of the system (0.96 × 101 PFU) is 10 times more sensitive than conventional methods (0.96 × 102 PFU). Furthermore, we validated the clinical utility of this automated system in various clinical specimens from emerging infectious diseases, including 20 plasma samples for Q fever and 13 (11 nasopharyngeal swabs and 2 saliva) samples for COVID-19. The system showed 100% sensitivity and specificity for detecting 33 samples of emerging infectious diseases, such as Q fever, other febrile diseases, COVID-19, human coronavirus OC43, influenza A, and respiratory syncytial virus A. Therefore, we envision that this automated sample-to-answer diagnostic system will show high potential for diagnosing emerging infectious diseases in various clinical applications. © 2023 Elsevier B.V.

Unlocking G-Quadruplexes as Targets and Tools against COVID-19.

The applicability of G-quadruplexes (G4s) as antiviral targets, therapeutic agents and diagnostic tools for coronavirus disease 2019 (COVID-19) is currently being evaluated, which has drawn the extensive attention of the scientific community. During the COVID-19 pandemic, research in this field is rapidly accumulating. In this review, we summarize the latest achievements and breakthroughs in the use of G4s as antiviral targets, therapeutic agents and diagnostic tools for COVID-19, particularly using G4 ligands. Finally, strength and weakness regarding G4s in anti-SARS-CoV-2 field are highlighted for prospective future projects.

Nanoparticles for vaccine and gene therapy: Overcoming the barriers to nucleic acid delivery.

Nucleic acid therapeutics can be used to control virtually every aspect of cell behavior and therefore have significant potential to treat genetic disorders, infectious diseases, and cancer. However, while clinically approved to treat a small number of diseases, the full potential of nucleic acid therapeutics is hampered by inefficient delivery. Nucleic acids are large, highly charged biomolecules that are sensitive to degradation and so the approaches to deliver these molecules differ significantly from traditional small molecule drugs. Current studies suggest less than 1% of the injected nucleic acid dose is delivered to the target cell in an active form. This inefficient delivery increases costs and limits their use to applications where a small amount of nucleic acid is sufficient. In this review, we focus on two of the major barriers to efficient nucleic acid delivery: (1) delivery to the target cell and (2) transport to the subcellular compartment where the nucleic acids are therapeutically active. We explore how nanoparticles can be modified with targeting ligands to increase accumulation in specific cells, and how the composition of the nanoparticle can be engineered to manipulate or disrupt cellular membranes and facilitate delivery to the optimal subcellular compartments. Finally, we highlight how with intelligent material design, nanoparticle delivery systems have been developed to deliver nucleic acids that silence aberrant genes, correct genetic mutations, and act as both therapeutic and prophylactic vaccines. This article is categorized under: Nanotechnology Approaches to Biology > Cells at the Nanoscale Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.