RNA Imaging for Development of COVID-19 Test Kits

The detection of SARS-CoV-2 infection can be performed from detecting the presence of the virus in terms of the nucleic acid level and the antibody level to measure whether the body has responded to the infection. Creative Biolabs' molecular biology and immunology experts have extensive experience in developing in vitro diagnostic assays. Using our advanced RNA imaging technology, we can help customers accelerate the process of developing high-quality COVID-19 test kits.

An Urgent Need for Rapid and Reliable COVID-19 Test Kits

The COVID-19 epidemic has shown a global spread. As of April 14, 1,837,101 cases of infection have been diagnosed globally, with a total of 116,248 deaths. Due to limited detection capabilities, as of March 2020, there is no country had reliable data on the prevalence of the virus in its population. Practice has proved that universal testing and screening of the population and early isolation and treatment of those who test positive are effective means of containing the spread of the epidemic and preventing the aggravation of the patient's condition. Therefore, the development of kits that can quickly and reliably detect SAS-CoV-2 nucleic acids has become an urgent need.

Fig.1 Trend of confirmed COVID-19 cases in multiple countries in North America (left) and Europe (right).

Creative Biolabs’ RNA aptamer-Lemon for RNA Imaging and Development of COVID-19 Test Kits

PCR is the earliest and most popular method for detecting nucleic acids. PCR amplification products are usually visualized by gel electrophoresis and nuclear acid intercalating fluorescent dyes. The real-time or quantitative PCR (qPCR) currently developed can monitor the generation of nucleic acid products in real time by the amount of fluorescence generated, avoiding the use of gel electrophoresis, but it will increase the time, complexity and cost of the experiment.

The discovery of fluorescent RNA aptamers brings exciting hope for the successful amplification of target RNA sequences. This technology was used to monitor in vitro transcription, and now Creative Biolabs has optimized and improved it, breakthrough combining their synthesis and amplification and applying it to isothermal experiments. Through SELEX screening technology, we obtained RNA aptamer-Lemon which can bind fluorescent dye specifically and with high affinity. Lemon's binding affinity for thiazole orange-based ligand (TO1-Biotin) can reach the nanomolar level, and once combined with fluorogenic ligands, it can enhance its brightness by up to 4,000 times, with significant background-free performance. It is particularly noteworthy that Lemon is highly resistant to magnesium concentrations and can play a role in a wide range of monovalent metal ion concentrations, which are commonly used in in vitro assays. By nesting nucleic acid sequence-based amplification (NASBA) primers and modifying the internal set of NASBA primers to encode fluorescent Lemon aptamers, we can detect RNA templates with attoMolar (aM, RNA molecules per μL) concentration. This result greatly ensures the sensitivity of RNA detection. And compared with MS2-tdMCP-mCherry dual-labeled mRNAs, RNA imaging technology based on Lemon's fluorogenic properties can significantly enhance signal-to-noise ratio.

The experimental results show that nested Lemon NASBA can even robustly and reliably detect low concentrations of RNA templates in the presence of a considerable competitive templates. These properties indicate that Lemon can be used as an attractive technology for developing RNA detection-based COVID test kits.

If you are interested in our RNA imaging technology RNA aptamer-Lemon and are planning to put it into the development of COVID test kits, please feel free to contact us.

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