Weekly CRISPR Digest

CRISPR Based Diagnostics

CRISPR is a powerful tool for precisely editing DNA sequences in living cells, allowing researchers to study gene function and develop novel therapies for cancer and genetic diseases. While CRISPR is most commonly associated with gene editing, it also has a range of other potential applications, including in diagnostic testing.

Diagnostic testing is a critical component of modern medicine, allowing doctors to identify and treat diseases in their early stages. Traditional diagnostic methods, such as PCR and ELISA, can be time-consuming, error-prone, and often require specialized equipment. However, CRISPR-based diagnostic techniques can offer a more efficient and accurate approach to disease detection in the field or at point-of-care. CRISPR-based nucleic acid detection assays detect specific RNA or DNA sequences associated with a particular disease or pathogen, with potential applications in infectious disease diagnosis, genetic testing, and cancer detection.

How CRISPR Diagnostics Work

The principle behind these assays is simple: if the target sequence is present in a sample, the CRISPR system cleaves a reporter molecule, producing a signal to indicate the presence of the target sequence. Standard signal methods such as colorimetric, fluorescence, and lateral flow detection can be used in CRISPR-based diagnostic systems. The main advantages of CRISPR-based nucleic acid detection assays are their sensitivity and flexibility. These assays can detect minimal amounts of genetic material, making them ideal for detecting diseases in their early stages.

Additionally, some CRISPR-based diagnostic systems require minimal sample preparation, reducing the cost and time needed for diagnostic testing. This allows for testing in the field with a portable device, making CRISPR assays ideal for use in remote and resource-limited settings. Finally, because CRISPR can be programmed to target any specific RNA or DNA sequence, these assays can be adapted for a wide range of applications. However, additional research and development is required to improve accuracy and speed further while reducing the cost of various CRISPR-based diagnostic assay systems.

CRISPR-Based Diagnostic Systems

One of the most well-known examples of CRISPR-based nucleic acid detection assays is the SHERLOCK (Specific High Sensitivity Enzymatic Reporter UnLOCKing) system, developed by researchers at the Broad Institute of MIT and Harvard and commercialized by Sherlock Biosciences. The SHERLOCK system uses a CRISPR-Cas13a system to detect specific RNA or DNA sequences associated with diseases such as Zika, dengue fever, or COVID-191,2. The system is highly sensitive and specific, detecting as few as ten copies of the target sequence in a sample.

Another example of a CRISPR-based diagnostic assay is DETECTR (DNA Endonuclease Targeted CRISPR Trans Reporter), developed by researchers at UC Berkeley and commercialized by Mammoth Biosciences. DETECTR uses CRISPR-Cas12a system to detect specific DNA sequences associated with diseases such as HPV (human papillomavirus) and cancer3,4. The system can detect DNA mutations associated with cancer development, allowing doctors to identify and treat the disease in its early stages.

Additional CRISPR-based diagnostic systems under development include: HOLMES (DNA & RNA viruses)5, NASBACC (Zika)6, CRISPR-mediated DNA FISH system (MRSA)7, CAS-EXPAR (Listeria monocytogenes) 8, LEOPARD (SARS-CoV2)9, igRNA (HIV)10, and nCATS (cancer)11.

CRISPR-based diagnostic assays are also being developed for various other applications, including detecting foodborne pathogens and environmental pollutants. For example, researchers have developed a CRISPR-based biosensor that can detect the presence of E. coli in food samples12. The biosensor uses CRISPR to target specific DNA sequences associated with the bacteria, allowing food safety inspectors to quickly and accurately identify contaminated samples.