Rapid and facile detection of HBV with CRISPR/Cas13a

SHERLOCK, a novel CRISPR-Cas13a-based assay for detection of infectious bursal disease virus

Infectious bursal disease (IBD) is an extremely contagious viral infection that primarily affects young chicks, leading to significant economic losses in the poultry industry. The disease is caused by a double-stranded RNA virus of the genus Avibirnavirus, family Birnaviridae, namely, the infectious bursal disease virus (IBDV). Unfortunately, current methods for detecting IBDV lack adequate sensitivity. Accordingly, the advantages of the Specific High Sensitivity Enzymatic Reporter UnLOCKing (SHERLOCK) assay were employed to develop an ultrasensitive assay (IBD-SHERLOCK assay) for the detection of IBDV in clinical chicken tissues. The assay comprises two steps: isothermal preamplification of the target RNA through reverse transcription recombinase polymerase amplification (RT-RPA) and a subsequent detection step, which is based on the CRISPR-Cas13a system. The integration of lateral flow (LFD) visual detection of the IBD-SHERLOCK products strengthens the feasibility of the assay for use as a point-of-care test in chicken farms. Compared with RT-qPCR, this method exhibited ultra-analytical and clinical sensitivity. The assay has a lower detection limit of 5 aM, which is equivalent to three IBDV-RNA molecules. The assay demonstrated the ability to detect IBDV-RNA in 70 clinical field samples, 15 of which tested negative by RT-qPCR. This evidence highlights its superior sensitivity and potential for early detection of IBDV in chicken tissues. This study effectively established and verified a CRISPR-based diagnostic test for the early detection of IBDV in clinical chicken tissues, demonstrating remarkable specificity and sensitivity. The IBD-SHERLOCK assay can be used as a highly sensitive point-of-care diagnostic tool in chicken farms.

Multiple signal amplification strategy for ultrasensitive sensing of Mycobacterium bovis based on 8-17 DNAzyme and CRISPR-Cas13a

Bovine tuberculosis caused by Mycobacterium bovis is not only responsible for economic losses but can also seriously jeopardize human health. Therefore, for the ultra-sensitive detection of M. bovis, a novel triple-cycle amplification system was developed based on 8-17 deoxyribozyme (DNAzyme), clustered regularly interspaced short palindromic repeats-associated protein 13a (CRISPR-Cas13a)-mediated cleavage cycles and the catalytic hairpin assembly (CHA) reaction (termed as DzCCR). In the presence of the target, the A-sequence containing 8-17 DNAzyme fragments was released from A-B using a strand displacement reaction, which could specifically cleave the HX-gRNA probe, releasing the sequence of gRNA and H and realizing the first signal amplification. Then, the released gRNA could bind to the Cas13a-g complex and activate the trans-cutting ability of Cas13a to re-cut RNA bulge sequences in HX-gRNAs, achieving the second signal amplification. Moreover, the H-sequence generated by the upstream 8-17 DNAzyme and Cas13a cleavage reaction further triggered the CHA, allowing the G-quadruplex dimer to be exposed, realizing signal output by adding thioflavin T (THT), and thereby achieving the third signal amplification. Benefiting from the triple signal amplification, the DzCCR system could quantitatively detect the M. bovis target down to a concentration of 0.5 fM with a linear calibration range from 1 to 500 fM. Furthermore, we investigated the ability of this system to detect M. bovis in real samples by standard addition method, the recovery ranged from 92.6% to 107.5%, and the relative standard deviations (RSD) ranged from 1.9% to 4.1%. Owing to the constant temperature and high sensitivity, the proposed strategy could be used as a new approach for the detection of M. bovis.

From Origin to the Present: Establishment, Mechanism, Evolutions and Biomedical Applications of the CRISPR/Cas-Based Macromolecular System in Brief

Advancements in biological and medical science are intricately linked to the biological central dogma. In recent years, gene editing techniques, especially CRISPR/Cas systems, have emerged as powerful tools for modifying genetic information, supplementing the central dogma and holding significant promise for disease diagnosis and treatment. Extensive research has been conducted on the continuously evolving CRISPR/Cas systems, particularly in relation to challenging diseases, such as cancer and HIV infection. Consequently, the integration of CRISPR/Cas-based techniques with contemporary medical approaches and therapies is anticipated to greatly enhance healthcare outcomes for humans. This review begins with a brief overview of the discovery of the CRISPR/Cas system. Subsequently, using CRISPR/Cas9 as an example, a clear description of the classical molecular mechanism underlying the CRISPR/Cas system was given. Additionally, the development of the CRISPR/Cas system and its applications in gene therapy and high-sensitivity disease diagnosis were discussed. Furthermore, we address the prospects for clinical applications of CRISPR/Cas-based gene therapy, highlighting the ethical considerations associated with altering genetic information. This brief review aims to enhance understanding of the CRISPR/Cas macromolecular system and provide insight into the potential of genetic macromolecular drugs for therapeutic purposes.

Advancements of CRISPR technology in public health-related analysis

Pathogens and contaminants in food and the environment present significant challenges to human health, necessitating highly sensitive and specific diagnostic methods. Traditional approaches often struggle to meet these requirements. However, the emergence of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) system has revolutionized nucleic acid diagnostics. The present review provides a comprehensive overview of the biological sensing technology based on the CRISPR/Cas system and its potential applications in public health-related analysis. Additionally, it explores the enzymatic cleavage capabilities mediated by Cas proteins, highlighting the promising prospects of CRISPR technology in addressing bioanalysis challenges. We discuss commonly used CRISPR-Cas proteins and elaborate on their application in detecting foodborne bacteria, viruses, toxins, other chemical pollution, and drug-resistant bacteria. Furthermore, we highlight the advantages of CRISPR-based sensors in the field of public health-related analysis and propose that integrating CRISPR-Cas biosensing technology with other technologies could facilitate the development of more diverse detection platforms, thereby indicating promising prospects in this field.

The SHERLOCK Platform: An Insight into Advances in Viral Disease Diagnosis

Persistence and prevalence of microbial diseases (pandemics, epidemics) is the most alarming threats to the human resulting in huge health and economic losses. Rapid detection and understanding of the disease dynamics by molecular biotechnology tools allow for robust reporting, treatment and control of diseases. As per WHO, the optimal diagnostic approach should be quick, specific, sensitive, without a stringed instrument, and low cost. The drawbacks of traditional detection techniques promote the use of CRISPR-mediated nucleic acid detection methods such as SHERLOCK as detection method. It takes advantage of the unexpected in vitro features of CRISPR-Cas system to develop field-deployable sensitive detection tools. Previously, CRISPR-mediated diagnostic methods have extensively been reviewed particularly for SARS-COV-2 detection, but it fails to provide the insight into advances of this technique. This study is the first attempt to review the advances of SHERLOCK approach as diagnostic tool for viral diseases detection. Variations of SHERLOCK mechanism for improved efficiency are discussed. Particularly integrated SHERLOCK approaches in terms of extraction-free assay and Bluetooth-enabled detection are reviewed to access their feasibility for the development of simpler and cost-effective diagnostic toolkits. Insight in to perks and limitations of diagnostic methods indicates its potential as ultimate diagnostic instrument for disease management.