When it comes to the diagnosis of COVID-19, time is of the essence. The quicker the diagnosis, the faster is the chance of mitigating the risks associated with the deadly infection. Now researchers have validated a cutting-edge CRISPR-based COVID-19 diagnostic test that can detect the virus in the sample in 20 minutes.
In a new study, the researchers from the University of Connecticut have validated the clinical viability of the method—which they began developing in March 2020—utilizing COVID-19 clinical swab samples. Also, a low-cost hand warmer was used as an incubator to detect the clinical sample.
"Such simple, portable and sensitive detection platform has the potential to provide rapid and early diagnostics of COVID-19 and other infectious diseases at home, in doctor's office, and even at drive-thru testing sites," explained Changchun Liu, lead author of the study, in a statement.
Developing a Low-cost Method of Detection
In March, the scientists began developing an inexpensive, CRISPR-based diagnostic method for the detection of infectious diseases such as the novel coronavirus (SARS-CoV-2)-caused COVID-19 and HIV (human immunodeficiency virus). The method, which is known as the "All-In-One-Dual CRISPR-Cas12a" (AIOD-CRISPR) aids in simple, quick and ultrasensitive visual detection of SARS-CoV-2, meant for use in small medical facilities or homes.
Currently, Nucleic acid amplification testing (PCR/RT-PCR) is the most specific and sensitive methods used for the early detection of disease-causing pathogens. However, it is not ideal for rapid with-patient or point-of-care diagnostics. This unfeasibility is caused by the requirement of specialized laboratory equipment and trained technicians. In the case of highly virulent pathogens, real-time monitoring is crucial in preventing the spread of the diseases.
Rapid Results Using Inexpensive Equipment
In the new study, the authors investigated the AIOD-CRISPR technique using RNA extracted from clinical COVID-19 swab samples. The samples contained eight that were COVID-19 positive. To ascertain the reliability of the process, all the samples were tested twice in two separate trials. All the eight COVID-19 positive samples were detected to be positive in 40 minutes and were confirmed through visual detection. Also, the results were accordant with those acquired by the RT-PCR method.
What also added to the inexpensive nature was the use of a low-cost hand warmer as an incubator which eliminated the requirement of an electric incubator. The AIOD-CRISPR tubes were placed over an air-activated hand warmer directly, and the results were viewable under an LED light with the naked eye.
Two of the COVID-19 positive samples that were incubated using the hand warmer were detected visually, and their status recognized as positive, in 20 minutes. Dr. Liu concluded, "The usage of disposable hand warmers to heat the AIOD-CRISPR assay eliminates need for expensive electric equipment, enabling instrument-free point of care molecular diagnostics of COVID-19."
Another Potential Rapid Test
The new test follows two other diagnostic techniques that may one day serve as potential methods of combating COVID-19. In April, several institutions in Guangzhou, China collaborated to develop a test that detects antibodies against the novel coronavirus in only 10 minutes. It leveraged a testing technique known as a lateral flow immunoassay (LFA).
Recently, researchers from Xuzhou Medical University in China announced the development of another CRISPR-based detection method. CRISPR-COVID method results within a duration as short as 40 minutes.