Researchers at the University of Illinois Urbana-Champaign have developed a sensor that can rapidly detect a virus in a sample. It can also identify whether the viral particles are still infectious. So far, the researchers have trialed the technology to detect human adenovirus and SARS-CoV-2. It can provide an answer between 30 minutes and two hours and uses DNA aptamers and nanopore technology to detect infectious viral particles. With some people still testing positive for COVID-19 long after their illness has passed, this new approach may help to put minds at ease about the risk of transmission.
PCR testing has been the cornerstone of disease monitoring during the COVID-19 pandemic. The test is highly sensitive, but doesn’t discriminate between active and infectious viral particles, and ‘dead’ particles that pose no risk of disease transmission. In certain cases, people will test positive for COVID-19 long after their illness has passed and when they are likely no longer infectious. Developing a rapid test that enables such people to determine that they are no longer infectious would be helpful.
“With the virus that causes COVID-19, it has been shown that the level of viral RNA has minimal correlation with the virus’s infectivity. In the early stage when a person is infected, the viral RNA is low and difficult to detect, but the person is highly contagious,” said Yi Lu, a researcher involved in the study, in a University of Illinois press release. “When a person is recovered and not infectious, the viral RNA level can be very high. Antigen tests follow a similar pattern, though even later than viral RNA. Therefore, viral RNA and antigen tests are both poor in informing whether a virus is infectious or not. It may result in delayed treatment or quarantine, or premature release of those who may still be contagious.”
This latest test allows researchers to quickly probe a sample for infectious particles. Aside from testing samples from patients, the system may help researchers to quickly rule in or out various disinfection techniques, based on their effect on viral particles.
“The infectivity status is very important information that can tell us if patients are contagious or if an environmental disinfection method works,” said Ana Peinetti, another researcher involved in the study. “Our sensor combines two key components: highly specific DNA molecules and highly sensitive nanopore technology. We developed these highly specific DNA molecules, named aptamers, that not only recognize viruses but also can differentiate the infectivity status of the virus.”