A new sensor detects if a virus exists and whether it is infectious. This distinction is crucial for controlling the viral spread.
Researchers at the University of Illinois Urbana-Champaign, with collaborators, developed the sensor. It integrates nanopore sensing and DNA fragments to detect and target infectious viruses in just minutes. The sensor was tested with the two most important viruses that cause infection worldwide, the human adenovirus (COVID-19) and the human adenovirus.
Yi Lu, a professor emeritus of chemistry, and Benito Marinas (a professor of civil-environmental engineering) co-led the research with Lijun Rong, a University of Illinois Chicago professor; Omar Azzaroni of the National University of La Plata, Argentina; and Maria Eugenia Toimil-Molares of the GSI Helmholtz Centre for Heavy Ion Research, Germany. Their findings were published in the Science Advances journal.
Ana Peinetti was the first author of this study. She researched while she was a postdoctoral researcher in Illinois. Now, she heads a research team at the University of Buenos Aires. “Our sensor comprises two components: susceptible nanopore technology and particular DNA molecules. These specific DNA molecules, aptamers, were created to recognize viruses and distinguish the infectivity status.
PCR tests are the “gold standard” for viral detection. However, they cannot detect infectious material or determine if a person has it. Researchers said this could make it harder to contain and track viral outbreaks.
“With the virus that causes COVID-19, it has been demonstrated that the virus’s viral RNA level has a minimal correlation with its infectivity. Lu stated that although the virus is not easy to detect in the initial stages of infection, it is very contagious. The viral RNA levels can rise if a person is cured and is not infected. Although antigen tests are more accurate than viral RNA, they follow the same pattern. Antigen tests and viral RNA are poor at determining whether a virus has been infected. This could lead to delayed treatment, quarantine, and premature release of contagious individuals.
Plaque assays are tests that detect the infectious virus. However, they require special preparation and several days of incubation before results can be obtained. Researchers report that the new sensing technique can produce results in as little as 30 minutes to 2 hours. It does not require pre-treatment and can be used with viruses resistant to laboratory growth.
Marinas stated that it is crucial to differentiate between infectious and non-infectious viruses, as well as detect small amounts of untreated samples that may contain other contaminants. This is important for quick diagnosis of patients in the early stages of infection and for monitoring environmental conditions.
Marinas stated that human adenovirus was chosen to test our sensor as it is an emerging viral pathogen in water. Marinas noted that the ability to detect infectious adenovirus, even in the presence of non-infectious viruses in water and other potentially harmful background substances in wastewaters or contaminated waters, is a novel and unprecedented approach. This technology has the potential to offer more robust protection for public and environmental health.
The sensing technology could also detect other viruses by altering the DNA to target pathogens. Similar to the PCR probes and DNA aptamers, the DNA aptamers can be easily made with readily available DNA synthesizers. Lu, now a professor at The University of Texas, Austin, stated that nanopore sensors are commercially available. This makes the sensing technique easily scalable.
Researchers are currently improving the sensors’ selectivity and sensitivity. They are also integrating DNA aptamers with other detection methods, such as color-changing dipsticks and sensors that work with smartphones to reduce the need to purchase special equipment. Researchers hope their technology will help understand the mechanisms of infection by allowing them to differentiate between non-infectious and infectious viruses.
Marinas stated that the aptamer technology could also be used to develop multichannel platforms to detect other emerging waterborne virus pathogens of public or environmental concern, such as enteroviruses and noroviruses or variants of the COVID-19 virus.
