Sensitive Detection of a Single-Nucleotide Polymorphism in Foodborne Pathogens Using CRISPR/Cas12a-Signaling ARMS-PCR

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.

Establishment of a simple, sensitive, and specific ASFV detection method based on Pyrococcus furiosus argonaute

African swine fever (ASF), which is casued by African swine fever virus (ASFV), is a fatal infectious disease of pigs that results in significant losses to the breeding industry. Therefore, screening and detection are crucial for the control and prevention of the ASFV. Argonaute is a new detection tool that is being extensively used due to its high specificity and programmability. This study reports on a new nucleic acid assay method, termed REPD, which uses recombinase-aided amplification and restriction endonuclease-assisted Pyrococcus furiosus argonaute (PfAgo) detection. One-pot REPD was developed for the detection of ASFV. The one-pot REPD could detect a single copy of ASFV nucleic acid and showed no cross-reactivity with other pathogens. Detection in clinical samples was 100% consistent with the results of real-time PCR analysis. The results showed that the one-pot REPD assay is convenient, sensitive, specific, and potentially adaptable to the detection of ASFV. In summary, this study highlights a novel method that can be employed for the detection of pathogens.

CRISPR/Cas13a-based single-nucleotide polymorphism detection for reliable determination of ABO blood group genotypes

The ABO blood group plays an important role in blood transfusion, linkage analysis, individual identification, etc. Serologic methods of blood typing are gold standards for the time being, which require stable typing antisera and fresh blood samples and are labor intensive. At present, reliable determination of ABO blood group genotypes based on single-nucleotide polymorphisms (SNPs) among A, B, and O alleles remains necessary. Thus, in this work, CRISPR/Cas13a-mediated genotyping for the ABO blood group by detecting SNPs between different alleles was proposed. The ABO*O.01.01(c.261delG) allele (G for the A/B allele and del for the O allele) and ABO*B.01(c.796C > A) allele (C for the A/O allele and A for the B allele) were selected to determine the six genotypes (AA, AO, BB, BO, OO, and AB) of the ABO blood group. Multiplex PCR was adapted to simultaneously amplify the two loci. CRISPR/Cas13a was then used to specifically differentiate ABO*O.01.01(c.261delG) and ABO*B.01(c.796C > A) of A, B, and O alleles. Highly accurate determination of different genotypes was achieved with a limit of detection of 50 pg per reaction within 60 min. The reliability of this method was further validated based on its applicability in detecting buccal swab samples with six genotypes. The results were compared with those of serological and sequencing methods, with 100% accuracy. Thus, the CRISPR/Cas13a-mediated assay shows great application potential in the reliable identification of ABO blood group genotypes in a wide range of samples, eliminating the need to collect fresh blood samples in the traditional method.

Cas-based bacterial detection: recent advances and perspectives

Persistent bacterial infections pose a formidable threat to global health, contributing to widespread challenges in areas such as food safety, medical hygiene, and animal husbandry. Addressing this peril demands the urgent implementation of swift and highly sensitive detection methodologies suitable for point-of-care testing and large-scale screening. These methodologies play a pivotal role in the identification of pathogenic bacteria, discerning drug-resistant strains, and managing and treating diseases. Fortunately, new technology, the CRISPR/Cas system, has emerged. The clustered regularly interspaced short joint repeats (CRISPR) system, which is part of bacterial adaptive immunity, has already played a huge role in the field of gene editing. It has been employed as a diagnostic tool for virus detection, featuring high sensitivity, specificity, and single-nucleotide resolution. When applied to bacterial detection, it also surpasses expectations. In this review, we summarise recent advances in the detection of bacteria such as Mycobacterium tuberculosis (MTB), methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (E. coli), Salmonella and Acinetobacter baumannii (A. baumannii) using the CRISPR/Cas system. We emphasize the significance and benefits of this methodology, showcasing the capability of diverse effector proteins to swiftly and precisely recognize bacterial pathogens. Furthermore, the CRISPR/Cas system exhibits promise in the identification of antibiotic-resistant strains. Nevertheless, this technology is not without challenges that need to be resolved. For example, CRISPR/Cas systems must overcome natural off-target effects and require high-quality nucleic acid samples to improve sensitivity and specificity. In addition, limited applicability due to the protospacer adjacent motif (PAM) needs to be addressed to increase its versatility. Despite the challenges, we are optimistic about the future of bacterial detection using CRISPR/Cas. We have already highlighted its potential in medical microbiology. As research progresses, this technology will revolutionize the detection of bacterial infections.

Combination of nucleic acid amplification and CRISPR/Cas technology in pathogen detection

Major health events caused by pathogenic microorganisms are increasing, seriously jeopardizing human lives. Currently PCR and ITA are widely used for rapid testing in food, medicine, industry and agriculture. However, due to the non-specificity of the amplification process, researchers have proposed the combination of nucleic acid amplification technology with the novel technology CRISPR for detection, which improves the specificity and credibility of results. This paper summarizes the research progress of nucleic acid amplification technology in conjunction with CRISPR/Cas technology for the detection of pathogens, which provides a reference and theoretical basis for the subsequent application of nucleic acid amplification technology in the field of pathogen detection.

In Situ Cas12a-Based Allele-Specific PCR for Imaging Single-Nucleotide Variations in Foodborne Pathogenic Bacteria

In situ profiling of single-nucleotide variations (SNVs) can elucidate drug-resistant genotypes with single-cell resolution. The capacity to directly "see" genetic information is crucial for investigating the relationship between mutated genes and phenotypes. Fluorescence in situ hybridization serves as a canonical tool for genetic imaging; however, it cannot detect subtle sequence alteration including SNVs. Herein, we develop an in situ Cas12a-based amplification refractory mutation system-PCR (ARMS-PCR) method that allows the visualization of SNVs related to quinolone resistance inside cells. The capacity of discriminating SNVs is enhanced by incorporating optimized mismatched bases in the allele-specific primers, thus allowing to specifically amplify quinolone-resistant related genes. After in situ ARMS-PCR, we employed a modified Cas12a/CRISPR RNA to tag the amplicon, thereby enabling specific binding of fluorophore-labeled DNA probes. The method allows to precisely quantify quinolone-resistant Salmonella enterica in the bacterial mixture. Utilizing this method, we investigated the survival competition capacity of quinolone-resistant and quinolone-sensitive bacteria toward antimicrobial peptides and indicated the enrichment of quinolone-resistant bacteria under colistin sulfate stress. The in situ Cas12a-based ARMS-PCR method holds the potential for profiling cellular phenotypes and gene regulation with single-nucleotide resolution at the single-cell level.

RatioCRISPR: A ratiometric biochip based on CRISPR/Cas12a for automated and multiplexed detection of heteroplasmic SNPs in mitochondrial DNA

Mitochondrial genetic diseases are often characterized by heteroplasmic single nucleotide polymorphisms (SNPs) where both wild-type (WT) and mutant-type (MT) coexist, making detection of accurate SNP abundance critical for diagnosis. Here, we present RatioCRISPR, an automated ratiometric biochip sensor based on the CRISPR/Cas12a system for detecting multiple heteroplasmic SNPs in mitochondrial DNA (mtDNA). The ratiometric sensor output is only influenced by the relative abundance of WT and MT, with minimal impact from sample concentration. Biochips allow the simultaneous detection of multiple SNP sites for more accurate disease diagnosis. RatioCRISPR can accurately detect 8 samples simultaneously within 25 min with a limit of detection (LOD) of 15.7 aM. We successfully detected 13 simulated samples of three mtDNA point mutations (m.3460G>A, m.11778G>A, and m.14484T>C), which lead to Leber's hereditary optic neuropathy (LHON) and set a threshold (60%) of heteroplasmy to evaluate disease risk. This automated and accurate biosensor has broad applications in diagnosing multiple SNPs, especially those with heteroplasmic variations, making it an advanced and convenient tool for mtDNA disease diagnosis.

Development of a tetra-primer ARMS-PCR for identification of sika and red deer and their hybrids

Accurate identification of deer-derived components is significant in food and drug authenticity. Over the years, several methods have been developed to authenticate these products; however, identifying whether female deer products are hybrids is challenging. In this study, the zinc finger protein X-linked (ZFX) gene sequences of sika deer (Cervus nippon), red deer (Cervus elaphus) and their hybrid offspring were amplified and sequenced, the X221 and X428 species-specific single nucleotide polymorphisms (SNP) loci were verified, and a tetra-primer amplification refractory mutation system (T-ARMS-PCR) assay was developed to identify the parent-of-origin of female sika deer, red deer, and their hybrid deer. The T-ARMS-PCR developed based on the X221 locus could identify sika deer, red deer, and their hybrid offspring according to the presence or absence of PCR product sizes of 486 bp, 352 bp, and 179 bp, respectively, just as X428 locus could identify sika deer, red deer, and their hybrid offspring according to the presence or absence of PCR product sizes of 549 bp, 213 bp, and 383 bp, respectively. Forty products labeled deer-derived ingredients randomly purchased were tested using this assay, and the results showed that the identification results based on the two SNP loci were utterly consistent with the actual sources. In addition, this method was found to be accurate, simple, convenient, and with high specificity, thus providing an essential technical reference for deer product species identification. It is also an important supplement to the identification methods of the original ingredients of existing deer products.

Recent Progress in Single-Nucleotide Polymorphism Biosensors

Single-nucleotide polymorphisms (SNPs), the most common form of genetic variation in the human genome, are the main cause of individual differences. Furthermore, such attractive genetic markers are emerging as important hallmarks in clinical diagnosis and treatment. A variety of destructive abnormalities, such as malignancy, cardiovascular disease, inherited metabolic disease, and autoimmune disease, are associated with single-nucleotide variants. Therefore, identification of SNPs is necessary for better understanding of the gene function and health of an individual. SNP detection with simple preparation and operational procedures, high affinity and specificity, and cost-effectiveness have been the key challenge for years. Although biosensing methods offer high specificity and sensitivity, as well, they suffer drawbacks, such as complicated designs, complicated optimization procedures, and the use of complicated chemistry designs and expensive reagents, as well as toxic chemical compounds, for signal detection and amplifications. This review aims to provide an overview on improvements for SNP biosensing based on fluorescent and electrochemical methods. Very recently, novel designs in each category have been presented in detail. Furthermore, detection limitations, advantages and disadvantages, and challenges have also been presented for each type.

Antibiotic resistance mechanism and diagnosis of common foodborne pathogens based on genotypic and phenotypic biomarkers

The emergence of antibiotic-resistant bacteria due to the overuse or inappropriate use of antibiotics has become a significant public health concern. The agri-food chain, which serves as a vital link between the environment, food, and human, contributes to the large-scale dissemination of antibiotic resistance, posing a concern to both food safety and human health. Identification and evaluation of antibiotic resistance of foodborne bacteria is a crucial priority to avoid antibiotic abuse and ensure food safety. However, the conventional approach for detecting antibiotic resistance heavily relies on culture-based methods, which are laborious and time-consuming. Therefore, there is an urgent need to develop accurate and rapid tools for diagnosing antibiotic resistance in foodborne pathogens. This review aims to provide an overview of the mechanisms of antibiotic resistance at both phenotypic and genetic levels, with a focus on identifying potential biomarkers for diagnosing antibiotic resistance in foodborne pathogens. Furthermore, an overview of advances in the strategies based on the potential biomarkers (antibiotic resistance genes, antibiotic resistance-associated mutations, antibiotic resistance phenotypes) for antibiotic resistance analysis of foodborne pathogens is systematically exhibited. This work aims to provide guidance for the advancement of efficient and accurate diagnostic techniques for antibiotic resistance analysis in the food industry.

CRISPR-based biosensors for pathogenic biosafety

Pathogenic biosafety is a worldwide concern. Tools for analyzing pathogenic biosafety, that are precise, rapid and field-deployable, are highly demanded. Recently developed biotechnological tools, especially those utilizing CRISPR/Cas systems which can couple with nanotechnologies, have enormous potential to achieve point-of-care (POC) testing for pathogen infection. In this review, we first introduce the working principle of class II CRISPR/Cas system for detecting nucleic acid and non-nucleic acid biomarkers, and highlight the molecular assays that leverage CRISPR technologies for POC detection. We summarize the application of CRISPR tools in detecting pathogens, including pathogenic bacteria, viruses, fungi and parasites and their variants, and highlight the profiling of pathogens' genotypes or phenotypes, such as the viability, and drug-resistance. In addition, we discuss the challenges and opportunities of CRISPR-based biosensors in pathogenic biosafety analysis.

Cas12a/blocker DNA-based multiplex nucleic acid detection system for diagnosis of high-risk human papillomavirus infection

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) proteins are an innovative tool in molecular diagnostics owing to their high specificity and modularity for target nucleic acid sequences. However, the sequence-indiscriminate trans-cleavage activity of the Cas protein renders multiplex detection challenging. In this study, we developed a Cas12a-based multiplex detection system by designing blocker DNA complementary to reporter DNA, which enables the simultaneous detection of two genes with a single Cas protein in a single reaction. As a proof of concept, we chose high-risk human papillomavirus (HPV) 16 and 18 as the model targets and incorporated recombinase polymerase amplification (RPA) and transcription reactions to achieve high accuracy and sensitivity. Using the proposed system, we detected the genes of both HPV 16 and 18 down to 1 aM within 80 min under isothermal conditions. We validated the performance of the system in detecting genomic DNA from various cell lines and clinical samples from cervical cancer patients with high specificity. The proposed system facilitated rapid multiplex detection of high-risk HPVs in a single reaction tube with only Cas12a, thus representing a more user-friendly and economical alternative to previous Cas protein-based multiplex detection assays. The proposed system has considerable potential for point-of-care testing and could be expanded to detect various nucleic acid biomarkers.

A universal and sensitive gene mutation detection method based on CRISPR-Cas12a

Single nucleotide mutations are highly related to the occurrence and development of cancer. The development of simple single nucleotide mutation detection methods with high sensitivity and specificity has great clinical significance for the prevention, diagnosis, treatment and prognosis evaluation of cancer. In recent years, CRISPR/Cas12a has been developed as a highly sensitive, simple and fast tool for nucleic acid detection. However, the specificity and universality of current detection methods based on it are still insufficient, so their clinical applications are limited. Herein, we developed a simple and rapid single nucleotide mutation detection method based on CRISPR/Cas12a system. This method not only solves the problem of PAM sequence restriction of CRISPR/Cas12a, but also significantly improves the specificity of CRISPR/Cas12a for single nucleotide mutation and greatly improves the sensitivity. We detected three clinically significant mutations, PTEN R130Q, BRAF V600E, and TP53 R248W, with a detection limit of 0.1%. Finally, we further verified the clinical practicability of this method. We selected TP53 R248W mutation site for testing. The accuracy of testing results for 10 clinical samples was as high as 100%. In conclusion, the detection method of specific PCR combined with CRISPR/Cas12a is simple, rapid, universal and highly sensitive. We believe that this method has promising application prospects in clinical diagnosis of cancer.

CRISPR-based nucleic acid diagnostics for pathogens

Pathogenic infection remains the primary threat to human health, such as the global COVID-19 pandemic. It is important to develop rapid, sensitive and multiplexed tools for detecting pathogens and their mutated variants, particularly the tailor-made strategies for point-of-care diagnosis allowing for use in resource-constrained settings. The rapidly evolving CRISPR/Cas systems have provided a powerful toolbox for pathogenic diagnostics via nucleic acid tests. In this review, we firstly describe the resultant promising class 2 (single, multidomain effector) and recently explored class 1 (multisubunit effector complexes) CRISPR tools. We present diverse engineering nucleic acid diagnostics based on CRISPR/Cas systems for pathogenic viruses, bacteria and fungi, and highlight the application for detecting viral variants and drug-resistant bacteria enabled by CRISPR-based mutation profiling. Finally, we discuss the challenges involved in on-site diagnostic assays and present emerging CRISPR systems and CRISPR cascade that potentially enable multiplexed and preamplification-free pathogenic diagnostics.

CRISPR/Cas Systems-Inspired Nano/Biosensors for Detecting Infectious Viruses and Pathogenic Bacteria

Infectious pathogens cause severe human illnesses and great deaths per year worldwide. Rapid, sensitive, and accurate detection of pathogens is of great importance for preventing infectious diseases caused by pathogens and optimizing medical healthcare systems. Inspired by a microbial defense system (i.e., CRISPR/ CRISPR-associated proteins (Cas) system, an adaptive immune system for protecting microorganisms from being attacked by invading species), a great many new biosensors have been successfully developed and widely applied in the detection of infectious viruses and pathogenic bacteria. Moreover, advanced nanotechnologies have also been integrated into these biosensors to improve their detection stability, sensitivity, and accuracy. In this review, the recent advance in CRISPR/Cas systems-based nano/biosensors and their applications in the detection of infectious viruses and pathogenic bacteria are comprehensively reviewed. First of all, the categories and working principles of CRISPR/Cas systems for establishing the nano/biosensors are simply introduced. Then, the design and construction of CRISPR/Cas systems-based nano/biosensors are comprehensively discussed. In the end, attentions are focused on the applications of CRISPR/Cas systems-based nano/biosensors in the detection of infectious viruses and pathogenic bacteria. Impressively, the remaining opportunities and challenges for the further design and development of CRISPR/Cas system-based nano/biosensors and their promising applications are proposed.