Two new COVID-19 tests developed in Brazil are patented

One of the technologies developed has RT-PCR-like precision and can analyze many patient samples simultaneously using a platform available in all Brazilian laboratories. A research group at the Federal University of São Carlos has also created a portable rapid test that detects the viral antigen in saliva and does not require a nasal swab.

By Maria Fernanda Ziegler  |  Agência FAPESP – Researchers at the Federal University of São Carlos (UFSCar) in Brazil have patented two innovative tests to detect SARS-CoV-2 in saliva. Both achieve a high level of sensitivity and, if produced on an industrial scale by partner companies, could enable mass testing of the Brazilian population, removing one of the bottlenecks that are hindering efforts to control the COVID-19 pandemic in the country.

One of the technologies involves an electrochemical sensor that analyzes the amount of viral spike protein in a saliva sample. “This is a rapid portable test model. Its sensitivity is very good, and it resembles the blood glucose monitoring devices [glucometers] used by diabetics. It consists of an electrochemical sensor that captures the spike protein. The result can be accessed in a matter of minutes via a smartphone,” Ronaldo Censi Faria, principal investigator for the project, told Agência FAPESP. Faria is a researcher at UFSCar’s Center for Exact Sciences and Technology (CCET).

A major advantage of the method over the antigen tests available on the market is that it does away with the need for a nasal swab to collect secretion.

The other test developed by the team detects viral RNA in saliva with a level of accuracy similar to RT-PCR, considered the gold standard for diagnosing COVID-19, but it is faster, and also cheaper because it uses fewer reagents.

Another advantage of this innovation is that it can analyze many samples from different patients simultaneously. This was achieved by adapting ELISA (enzyme-linked immunosorbent assay), the platform widely used by clinical laboratories throughout Brazil.

ELISA is mainly involved in tests to detect the presence of an antigen or an antibody in a sample. The platform consists of a microplate with 96 wells containing the viral protein that can be recognized by the human immune system so that samples from 96 individuals can be analyzed at the same time.

“The key innovation in the technique we’ve developed is our adaptation of the microplate generally used to detect antibodies. In our case, it detects the presence of genetic material [RNA] from the virus. This is novel and has never been done before,” Faria said. “ELISA is widely available. All Brazilian clinical laboratories use it. Our technology will therefore make diagnosing COVID-19 much faster and accessible to many more people. In future, we plan to use the innovation to develop tests for other diseases.”

The agility also derives from the fact that the test skips several stages of RT-PCR, which requires extraction of the genetic material, conversion of RNA to DNA, and DNA amplification. “Our test is more direct,” Faria said. “We detect genetic material by means of magnetic particles attracted by magnets. Adding the reagent produces a color that shows whether the result is positive or negative.”

Both the rapid electrochemical test and the colorimetric model with RT-PCR-like precision use magnetic particles. “We modified the particles to pick up the target, whether it’s the spike protein or viral RNA,” Faria said. “The method that captures the spike protein is electrochemical. A current is generated when the protein is detected. In the other method, after RNA capture we use a reagent that produces the color for a positive result.”

This strategy enhances the test’s sensitivity. “It makes diagnosis feasible even when the amount of genetic material in the sample is small. The magnetic particles are the key to the method we developed,” Faria said.

Both projects were supported by FAPESP and CAPES, the Brazilian Ministry of Education’s Coordination for the Improvement of Higher Education Personnel.

A factory making novel tests 

UFSCar’s Bioanalytics and Electroanalytics Laboratory (LaBiE) has developed several other tests. According to Faria, the methodology used in the tests to diagnose COVID-19 is an adaptation of devices that are being created to diagnose cancer, leishmaniasis, Hansen’s disease, zika, and Alzheimer’s disease.

“The electrochemical test is basically an adaptation for COVID-19 of a device we made to detect Alzheimer’s,” he said. “The colorimetric test, which is comparable to RT-PCR in terms of precision, is a completely novel technology. We hadn’t previously thought of this model for any other disease.”

Faria regularly partners with physicians and specialists in other areas. The device that detects Alzheimer’s, for example, was a collaboration with Márcia Cominetti, a professor in UFSCar’s Department of Gerontology. The COVID-19 tests were developed in collaboration with the group led by Ester Sabino, a professor at the University of São Paulo’s Medical School (FM-USP) and Institute of Tropical Medicine (IMT-USP), and with Matias Melendez, currently a researcher at Pequeno Príncipe Children’s Hospital in Curitiba (Paraná state).

Before they were patented, the tests were validated in saliva samples from patients treated at hospitals in São Carlos and São Paulo, achieving sensitivity over 90% in both cases. The researchers are now looking for partners to use the colorimetric method in the two cities’ schools.