New test to detect coronavirus in less than an hour

La polimerasa del fago phi29
Adaptada de Vega et al, (2010) PNAS

Margarita Salas, was the researcher that helped to develop new technology in detecting Covid-19 and it is proving to be a promising tool for dealing with one of the great challenges posed by the new SARS-CoV-2 virus; being able to detect it quickly, easily and effectively, particularly in asymptomatic patients. A team made up of researchers from the Spanish National Research Council (CSIC) and the Spanish National Cancer Research Centre (CNIO) has obtained funding from the Carlos III Health Institute to apply the DNA polymerase of the phi29 virus (phi29pol) to the early detection of the new coronavirus.

Phage polymerase phi29

One of Margarita Salas' greatest contributions to science was this biotechnological tool that allows very small samples of genetic material to be amplified millions of times, which facilitates their analysis. Phage phi29 polymerase is used worldwide in disciplines such as archaeology, forensic medicine and oncology.

"Its ability to amplify genetic material from very small, even damaged, samples gives us a clue that it can be an extremely sensitive method for detecting the presence of the virus' genetic material, and therefore confirming an infection, even in cases with a small viral load such as asymptomatic patients," says Felipe Cortés, head of the CNIO's DNA Breakdown and Topology Group and one of the coordinators of the new project.

Advantages over other detection methods

The current tests for detecting the RNA of the new coronavirus are based on RT-PCR techniques that require highly specialized equipment and personnel. This greatly limits their ability to perform massive tests and obtain results in a short time, which is most desirable in order to take timely action to isolate positive cases.

On the other hand, alternatives based on rapid antibody detection currently present important limitations in terms of sensitivity and fidelity.

In the case of phi29 virus polymerase, in addition to being capable of multiplying a sample of genetic material thousands or millions of times, its mechanism works even at room temperature, and it also allows the diagnosis of a large number of samples to be completed in less than an hour.

"This feature has also been key to developing the project, as it allows us to detect the virus at room temperature without the need for specialized equipment or technical personnel", adds Luis Blanco, Research Professor at the Centro de Biología Molecular Severo Ochoa (CBMSO), a joint centre of the CSIC and the Universidad Autónoma de Madrid and also the coordinator of the new project.

Simple technology to diagnose at street level

The aim is to develop a portable device (similar to a pregnancy test) that allows the simple, quick and reliable diagnosis of the disease, even at home. This methodology will also be adapted to detect the presence of the virus in the environment and on surfaces.

"This would allow us to diagnose on the street, even in the primary care centres themselves, nursing homes or other particularly sensitive places, thus avoiding sending samples to trained laboratories, facilitating logistics and preventing new infections," the researchers say.

When will it be ready?

The Covid-19 diagnostic method proposed in the project is based on an improvement of the enzyme, developed by Miguel de Vega, a CSIC researcher at the CBMSO. The research is already underway, and in a first phase, the sensitivity of the technique for detecting the virus will be studied, including clinical samples from patients. The second phase will consist of optimizing the system for subsequent application in the clinic.

The project managers expect to have the first version ready by the autumn, which could coincide with a possible outbreak of the disease.

Image: 3D model of the phi29 chimeric DNA polymerase variant called Qualify. Adapted from Vega et al, (2010) PNAS 107, 16506-11.

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