Akash Singh, Banaras Hindu University
COVID-19 rapid tests, which can detect the onset of the disease at the point of care, are in high demand. A research team from Monash University in Australia has developed an ultra-portable COVID-19 diagnostic tool. Based on the idea of loop-mediated isothermal amplification, they developed a self-contained, point-of-care nucleic acid amplification test for the identification of active COVID-19 infection (LAMP). The LAMP test is said to be 100 percent sensitive and specific for detecting at least 300 SARS-CoV-2 RNA copies per response. Easy-to-operate, the test does not require a skilled operator. The total time from sample to diagnosis is approximately 35 minutes. Rapid and effective testing in community settings is possible with this portable diagnostic platform, which has significant potential.
Types of tests for COVID-19:
As of now, COVID-19 can be detected using two types of tests:
- antibody tests based on serology
- molecular tests.
After infection, peripheral blood is tested for antibodies (IgM and/or IgG) to the SARS-CoV-2 virus. They are not found to accurately reflect active infection. Molecular tests detect viral materials directly in a specimen taken from an individual to indicate active infection, whereas virological tests detect viral materials indirectly through antibodies. Most molecular tests are based on nucleic acid amplification. These tests use either loop-mediated isothermal amplification (LAMP) or polymerase chain reaction (PCR). NAAT (Nucleic Acid Amplification Test), also known as a quantitative reverse transcription-polymerase chain reaction, is the current gold standard for testing for SARS-CoV-2 virus (RT-qPCR).
SARS-CoV-2 LAMP Assays:
The researchers of the study in discussion created four separate LAMP tests, two of which focused on the N gene and the other two on the E gene. As a result of sequence alignment, all 4 sets were able to detect both the standard SARS-CoV-2 strain and variants such as the UK strain (B.1.1.7, mutation).
A disposable sample collecting tube, a disposable cartridge, and a reusable control unit are the three major components of the device. A nasopharyngeal swab or saliva sample is obtained and placed inside a collecting tube containing deionized (DI) water to complete the test. The tube is then placed onto the cartridge. This cartridge contains a preloaded reaction chamber for the LAMP reaction and a lysing chamber for sample lysis/RNA extraction. The sample is drawn into Chamber 1 and heated for 5 minutes at 95 degrees Celsius. It is then transferred to Chamber 2, which contains the LAMP master-mix, and cooked for 30 minutes at 60 degrees Celsius. The colour of the reagent in Chamber 2 changes from pink to yellow when the SARS-CoV-2 virus is present. The colour of the reagent will remain pink if the sample does not include SARS-CoV-2.
Advantages and Prospects:
Reverse transcription (RT)-LAMP amplification is the foundation of the prototype. It’s done with a self-contained gadget that doesn’t require any specific lab equipment or an experienced operator. For the extraction of RNA from oropharyngeal swab samples for the detection of different viral targets, this approach has been proven to be efficient. This pocket-sized ultra-portable device is lightweight and easy to use, and it may be powered by batteries or a power bank. It takes about 35 minutes to get a straight result from a sample. By simply changing the LAMP primers, the device can be modified to test for various respiratory viruses.
In addition to the current gold standard of testing, the team acknowledged the importance of having affordable, easy-to-use, or even ultra-portable technologies for COVID-19 testing. As a result, this prototype will relieve strain on congested centralized laboratories by allowing testing to take place in community settings.
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References:
- Deng, H., Jayawardena, A., Chan, J. et al. An ultra-portable, self-contained point-of-care nucleic acid amplification test for diagnosis of active COVID-19 infection. Sci Rep11, 15176 (2021). https://doi.org/10.1038/s41598-021-94652-0
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Author info:
Akash Singh is a first-year master’s student of Biochemistry at Banaras Hindu University. He plans to pursue Ph.D. in the future. He aims to research and teach the young minds of the country.
Social media links: LinkedIn: https://www.linkedin.com/in/akash-singh-82b5811a2/
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