IPN scientists develop rapid diagnostic tests for COVID-19

Mexican

researchers

have adapted the use of chemical antibodies, such as aptameters , used for the detection of HPV , that could be useful for the detection of COVID-19 .

Aptameters

are small DNA or RNA molecules chemically synthesized that are able to adapt and look similar to a specific chemical process. This time, experts are looking to adapt them to the Spile (S) element, a protein present in SARS-CoV-2 .

“They are called aptameters because they are the aptest molecules in terms of interaction,” said the experts from the C enter of Advanced Research and Studies (CINVESTAV) of the National Polytechnic Institute (IPN) .

Luis Marat Álvarez

, the head of the project, explained the procedure they performed: “We used the ‘Spike' molecule present at the new coronavirus as a detection target, it is the most prominent protein in the surface of the virus and the one in charge of the infection of the host’s cells.”

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After obtaining the aptameters, it is possible to perform visual diagnostic tests that consist of a recognition biosensor and an element that transduces signals with the use of gold nanoparticles that help detect the interaction with the virus through the change of color it produces in the reagents.

The CINVESTAV researcher added that “the concept is very similar to rapid drug tests that are used at customs offices and airports; the sample of the substance touches the reagents if it changes its color, it means that the test is positive. Instead of analyzing substances, we want to know if a person has an active SARS-CoV-2 infection .”

The test would originally be red; if it turns blue with the patient’s sample, it would reveal the presence of the virus. “This would provide a simple and cheap test to identify active infections,” said the researcher.

Aptameters are produced in great amounts so there would be a sufficient supply of them for the creation of thousands of diagnostic tests .

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Moreover, the use of tests with aptameters is less expensive than the ELISA diagnosis , used for antibody detection, and than the current PCR tests.

Another benefit is that it does not require special equipment nor trained personnel, “it's totally in vitro .” The aptameters are synthesized in automatic machines available in Mexico.

Countries like China , Canada , and the UK have also invested in rapid coronavirus diagnostic tests based on aptameters, while the U.S. is performing trials on an experimental cancer drug based on the same kind of antibodies.

Meanwhile, the CINVESTAV is also working on another technique to detect the new coronavirus that shows results in 15 minutes in asymptomatic or mild cases that have the ability to infect others.

The technique developed by the CINVESTAV scientists has the objective of amplifying a viral gene in a specific way, which works by generating multiple copies of it so that it can be quickly detected.

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“Unlike the conventional PCR technique in which the sample is put under different temperature cycles, the one proposed by CINVESTAV researchers uses equipment that allows incubating the test at 65 C ,” CINVESTAV said.

“Since it does not require sophisticated (…) equipment it can be done where the patients are. It must be stressed that this technique has already been used at an international level for the detection of different pathogens, both from plants , animals , and humans .”

Currently, the test to detect the presence of the SARS-CoV-2 virus that causes the COVID-19 disease uses a molecular test that shows the presence of the genetic material of the virus; the problem is that its use is limited to its cost and the need for specialized facilities .

CINVESTAV scientists developed a portable test that works with a device made with a resistance. similar to those used in irons, that maintains a constant temperature of 65 C.

The physicians that perform the test can monitor the progress and the obtention of result through an app that is available on Android devices . The app sends the results via e-mail.

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Researcher Beatriz Xoconostle Cázares

, who participated in the project, explained that implementing this kind of test could be ideal for asymptomatic patients or those with mild symptoms, who would not need to go to hospitals treating COVID-19. This would allow them to recover at home and isolate themselves to limit the spread of the new coronavirus.

“In addition, by limiting contagions, we could prevent mutations in the genetic material of the virus since these changes can diversify to more or less aggressive variants of the pathogen and further complicate its control,” she said.

The rapid diagnostic test developed by the CINVESTAV is ready; the next step is to request the approval of the Institute for Epidemiological Diagnosis and Reference (INDRE) ; once this happens, hospitals and authorized laboratories will be able to implement it.

Beatriz Xoconostle mentioned that, in addition to the approval, economic investment is needed to escalate the production of the test, which includes portable equipment for on-site diagnosis and the diagnosis kits (the enzyme and other reagents that allow the amplification of the viral genetic material.)

In order to reduce the cost of this test, several reagents, which are usually purchased from supplies abroad, would be purified by the CINVESTAV .

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