And Brazilian scientific team has developed a test capable of detecting in urine the presence of SARS-CoV-2 antibodies with an accuracy comparable to existing tests based on blood serum.
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 an individual’s risk of infection.
It is a new Elisa platform -the laboratory test commonly used to detect antibodies in blood and an English acronym for absorption 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, using urine to detect antibodies would allow patients to collect their own samples and would eliminate the need for experts to draw blood and handle the samples.
Although urine tests are non-invasive, simple, convenient and safe, scientists had not until now studied whether this body fluid could be an alternative to blood serum for detecting SARS-CoV-2 virus-specific antibodies, according to an abstract. of the magazine.
To investigate, Fernanda Ludolf of the Federal University of Minas Gerais in Brazil and her team developed a urine-based Elisa test using the coronavirus protein N (recombinant nucleocapsid protein).
They used the assay 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 Elisa test whey-based, which is well established.
They found that the urine-based platform successfully detected the antibodies in 187 of the samples, demonstrating a sensitivity of 94%, compared to the 88% sensitivity of the serum-based test.
According to the scientists, the urine-based platform detected the antibodies with marginally better accuracy than the serum-based platform, although this difference was not statistically significant.
“Since we have identified antibodies against SARS-CoV-2 protein N in urine, the development of a urine Elisa test based on protein S or spike of the virus can also be feasible to cover other applications of serological testssuch as the detection of vaccine-induced antibodies,” the authors write.