NEC Corporation, a leader in the integration of IT and network technologies, and NEC Solution Innovators, on May 6, 2021, announced the successful development of artificial DNA aptamers that bind to the novel coronavirus (SARS-CoV-2). This breakthrough stems from the NEC Group's efforts to promote spatial monitoring business using aptamers, including the development of new biosensing systems, such as measuring equipment that can monitor spaces where various viruses, including SARS- CoV-2 and influenza viruses, are present. An aptamer is a nucleic acid (DNA or RNA) that recognizes and specifically binds to the conformation of a particular target molecule, such as a virus or protein. It is an artificially created SELEX technology that searches for sequences that bind strongly to a test target.
Overview of aptamers:
SARS-CoV-2 enters into human cells when the spike protein, Receptor-Binding Domain (RBD), on the surface of the virus binds to the Angiotensin-Converting Enzyme-2 (ACE2) receptors on the surface of human cells. The aptamer developed by NEC Solution Innovators targets RBD, which is the key to infection, then traps the virus by recognizing the three-dimensional structure of the RBD and binding very strongly to it (a dissociation constant indicating the strength of the binding between molecules is less than 1nM). This aptamer uses a new modified base called 'Base-appended-Base', which was developed by NEC Solution Innovators and Gunma University from 2014-17 supported by a grant for "Adaptable and Seamless Technology transfer Program through target-driven R&D" (A-STEP) from the Japan Science and Technology Agency (JSTA).
Three variants of SARS-CoV-2, including the original strain (WK521 Wuhan strain) and two mutant strains (TY7-501 Brazilian & QK002 UK strains) are being studied by academic laboratories in collaboration with the NEC Group. The binding assessment tests with aptamers were conducted in a Bio- Safety Level-3 (BSL3) laboratory, which is allowed to handle SARS- CoV-2. The binding assessment tests were conducted using the direct Enzyme-Linked Aptamer Assay (ELAA) method [a method to detect enzymatic activity in which a target protein or virus to be detected is adsorbed on a plate, and an enzyme such as Horse-Radish Peroxidase (HRP) or alkaline phosphatase is added to an aptamer], in which viruses were adsorbed onto plates and detected with enzyme-labeled aptamers. As a result, a strong binding of aptamers to SARS-CoV-2 was observed in all the three strains.
Future prospects:
NEC is developing a measuring device that enables spatial monitoring of SARS-CoV-2 by combining Membrane-type Surface Stress sensor (MSSs is a highly sensitive nano- mechanical sensor that utilizes electric read-out based on piezo-resistors and is capable of measuring/analyzing scents & odors & can be used for many other applications) and an aptamer that binds to SARS-CoV-2. This measuring device is designed to be used in spaces where people gather and spend time in close proximity, such as public facilities, restaurants, lodging facilities, event venues and offices. In fiscal 2021, NEC expects to provide a prototype of a fixed-type spatial monitoring measuring device for companies, universities and other research institutions that perform virus measurement & other measures. In addition, in fiscal 2022, NEC aims to provide a biosensing system that can be used for space monitoring and as an embedded device for equipment such as air conditioners.
"Going forward, through joint research in fiscal 2021, the NEC Group will accelerate the development of aptamers with stronger ability to inhibit infection, which will facilitate the aptamers' potential as an antiviral drug," said Yutaka Ukegawa, Senior Vice President, NEC Corporation. "These initiatives are in line with the NEC Group's aim to achieve NEC Safer Cities, which utilize state-of-the-art Information & Communication Technology (ICT) and biotechnology in support of vibrant communities," Ukegawa added.
