Its description is published in an article in the journal Science Advances and, according to those responsible, this technique offers a non-invasive method to assess the risk of infection of an individual.
This is a new Elisa platform - the laboratory test commonly used to detect antibodies in blood and an acronym in English for enzyme-linked immunosorbent assay - that detects antibodies against SARS-CoV-2 in urine instead of serum.
The analysis offers a non-invasive method that can be used to report the degree of exposure of a population to Covid-19 and to assess an individual's risk of infection, the authors note.
Unlike the popular serum-based Elisa test, the use of urine to detect antibodies would allow patients to collect their own samples and would eliminate the need for experts to draw blood and handle samples.
Although urine tests are non-invasive, simple, comfortable and safe, scientists had not until now studied whether this body fluid could constitute an alternative to blood serum to detect specific antibodies to the SARS-CoV-2 virus, according to an abstract of the magazine.
To investigate this, Fernanda Ludolf, from the Federal University of Minas Gerais in Brazil, and her team developed an Elisa test based on urine using the N protein of the coronavirus (recombinant nucleocapsid protein).
They used the test to evaluate 209 urine samples from 139 patients between 2 and 60 days after Covid-19 symptoms began, and compared their results with those of the well-established serum-based Elisa test.
They found that the urine-based platform successfully detected antibodies in 187 of the samples, demonstrating a sensitivity of 94 percent, compared to the 88 percent sensitivity of the serum-based test.
According to scientists, the urine-based platform detected the antibodies with marginally higher accuracy than the serum-based platform, although this difference was not statistically significant.
"Given that we have identified antibodies against the N protein of SARS-CoV-2 in urine, the development of a urine ELISA test based on the S or spike protein of the virus may also be feasible to cover other applications of serological tests, such as the detection of vaccine-induced antibodies," the authors write.
