Scientists at Duke University, USA, have developed a new test that can detect antibodies against the Sars-CoV-2 coronavirus with high precision and with a result in about an hour with just one drop of blood.
An article describing the test was published this Friday (25) in the scientific journal Science Advances, edited by the American Association for the Advancement of Science (AAAS), the same group that publishes the prestigious journal Science.
The device, including the screen on which the result is displayed, can be carried in a backpack and run on a battery, according to the researchers. The high sensitivity of the test and its portability would make it possible to expand serological examinations of the population and to know who has already had contact with the pathogen.
Antibody tests, however, give no indication of whether a person has the infection in the acute phase (at this point in time) and have limited potential to tell whether someone who has already contracted the virus or received an anti-Covid vaccine has, is protected.
Antibodies are proteins produced by the immune system that can prevent the virus from attaching to the body’s cells and causing an infection. The presence of these proteins indicates previous contact with the virus, but does not guarantee protection from the disease. There are other molecules produced by the immune system that form an important barrier to infection that cannot be detected in such tests.
According to the results, the device is able to detect and quantify multiple antibodies related to different parts of the virus. The test did not show false results and also indicated the presence of antibodies to four other types of coronavirus, demonstrating its potential to be used against other diseases even after the pandemic.
The technique used on the device is called microfluidics. It’s a microchip-based system through which liquids circulate and react with one another. If the reaction is positive, there will be a fluorescence emission indicating the result.
While it is not yet widely used, it is not new and has been in development for a number of years. The application for the detection of Sars-CoV-2 antibodies is unprecedented.
For Flávio da Fonseca, virologist at UFMG (Federal University of Minas Gerais) and President of the Brazilian Society of Virology (SBV), who was not involved in the research, the new test comes at the right time.
“After a year and a half of the pandemic, we want to know how the virus circulates in each country and whether people have generated an immune response to Sars-CoV-2 and that a good antibody test can react to it,” says the scientist.
According to Fonseca, the microfluidic test does not replace the current gold standard for the detection of infections in the acute phase – RT-PCR – but it is a better alternative to the rapid tests marketed today, which also detect antibodies, but with fluctuating quality (sometimes still gives false results) and does not display the amount of antibodies.
“It remains to be seen whether the system will bring advantages from a commercial point of view so that it can be used in Brazil,” says the scientist.
In the future, the test could confirm whether a person had contact with a variant of Sars-CoV-2, say the developers of the new test. Scientists are also developing a way for the test to detect biomarkers that could indicate whether an infected person is more likely to develop Covid-19 in its most severe form.