‘15-Minute’ Quick Diagnostic Testing for Newly Emerging Viruses
– Prof. Sung Key Jang of POSTECH developed a quick diagnostic testing for viral infections using aptamers.
– This new technology led to beginning of developing a new COVID-19 diagnostic system and a clinical treatment of the disease.
The novel coronavirus, named as COVID-19, began in Wuhan, China and is threatening all regions around the globe that the World Health Organization (WHO) has declared this outbreak a pandemic since the swine flu 11 years ago. When such a highly contagious and fatal new disease occurs, it is necessary to quickly identify infected individuals and quarantine them. The most important step in this procedure is to have a quick diagnosis of viral infection.
A research team from POSTECH recently developed a quick diagnostic testing for viral infections that can bring results in 15 minutes by using an aptamer (nucleic acid molecule), a kind of molecular capture. This new test can be applied to diagnosis of all novel viruses and is expected to be used in clinical applications as well.
Prof. Sung Key Jang, Dr. Junyoung Kwon, and Dr. Chandan Narayan of Department of Life Sciences, POSTECH with Aptamer Sciences (Inc.) developed a new method (designated as viro-SELEX) for discovering aptamers against membrane proteins. Using viro-SELEX, they were able to develop aptamers with high sensitivity and specificity for binding to target proteins which led to rapid 15-minute diagnosis of viral infections. Their new discovery is published in the renowned journals, Journal of Biomedical Nanotechnology and Analyst.
There are several ways to test viral infections including molecular assays, immunoassays, and virus cultivation. For COVID-19, molecular assays are used to diagnose, however, the whole diagnosis process is not convenient despite of its high sensitivity. It requires the samples to be sent to professional institutions for analysis, takes more than six hours to analyze, and is highly expensive. Virus cultivation takes even longer time to analyze from two to four weeks and is not appropriate for massive tests. Lastly, immunoassays for COVID-19 has not been developed yet. Unfortunately, there has not been a real-time diagnostic test for COVID-19 developed that can be tested on site where the samples are taken.
An aptamer is a nucleic acid that is composed of DNA or RNA. It is kind of a molecular capture that binds to various targets ranging from a low molecular weight compound to macromolecules such as proteins with high specificity and affinity. DNA aptamers are highly stable and therefore easy to transport and store. When the sequence of aptamer is known, it can be synthesized in mass at economical price. So, it is considered as a substitute for an antibody.
Aptamers are discovered through the process called, SELEX*1. However, it has been challenging to develop aptamers through the conventional SELEX method in cases of virus because its targeted molecules are membrane proteins.
The research team generated recombinant baculoviruses*2 (surrogate viruses) containing target proteins on the viral envelope instead of purifying the membrane proteins. They applied the surrogate viruses in the SELEX process (designated as viro-SELEX.
Based on this new method, they generated new aptamers that bound to viral envelope proteins, HA, of influenza virus. Also, they were able to develop a diagnosis kit that changed a color, indicating the infection of virus like a pregnancy test kit by using a pair of aptamers which bound to different areas of HA. If this kit is used for diagnosis of viral infections, 15 minutes is enough to know the result.
“We can develop aptamers that bind to the spike proteins of COVID-19 with high specificity and affinity by using this newly developed viro-SELEX method. And using the aptamers, we can make a quick diagnosis kit. Moreover, these aptamers may also protect healthy cells from COVID-19 infection through interaction and inactivation of spike proteins. In other words, these aptamers could serve as lead molecules for developing a clinical treatment.” said, Prof. Sung Key Jang.
Meanwhile, the research team began developing a diagnostic test for COVID-19 with Korea Research Institute of Chemical Technology, which has the facility to cultivate COVID-19, and Aptamers Science Inc., which developed a KFDA-approved diagnosis of lung cancer for the first time in the world. Their goal is to establish a platform that can rapidly develop diagnosis and treatment of a novel virus such as COVID-19, MERS, and SARS.
1. SELEX, Systematic Evolution of Ligands by Exponential Enrichment
It is also known as in vitro evolution. It is a method for generating nucleic acids that can bind to targeted molecules with high affinity.
This virus is pathogenic to insects but not harmful to humans. It is often used for producing proteins in mass.