Conversation with researcher Pilar Marco about her Covid-19 project

We talk with Pilar Marco, leader of the Nanobiotechnology for Diagnostics Group at the Institute for Advanced Chemistry of Catalonia, about the project POC4COVID.

Pilar Marco is the leader of the Nanobiotechnology for Diagnostics Group at the IQAC-CSIC.We want to develop new strategies for the diagnosis of Covid-19 in order to be able to produce reliable devices on a broad scale, to make them available to everybody. Hence, we are developing two technological devices: one based on optical detection, with a heat-sensitive substrate, and the other based on electrochemical detection. The first one would allow us the diagnosis of Covid-19 even with a cell-phone camera, whereas the second would detect viral RNA, viral proteins and any antibody developed as a response to the infection.

A good diagnostic system could accurately detect the disease in the very early stages of the disease, with a high sensitivity and specificity. In some cases, the diagnostic tools could provide more information, such as the patient’ stage of the disease, severity and prognosis. In the case of Covid-19, there are many devices in the market, although not all of them have been adequately developed and validated, as it has been evidenced after some actions taken by various governments to acquire tests [some of which turned out to be defective]. Moreover, all tests are not the same nor provide the same information.

Nowadays, Covid-19 available tests fit into two categories: category A, the ones that detect the SARS-CoV-2 virus, and category B, the ones that detect the previous exposition to the virus or, more accurately, the immune response of the human body to the infection. In the first one, there are two subtypes: the A1 type detects the genetic material of the virus through retrotranscription associated to the chain reaction of the polymerase or RT-RCP; whereas the A2 type detects components of the virus, such as the surface proteins.

There are two types of tests: the ones that detect the SARS-CoV-2 virus and the ones that detect the previous exposition to the virus or the immune response of the human body to the infection

The RT-RCP tests (A1) are the recommended ones by the World Health Organisation and European Centre for Disease Prevention and Control for Covid-19 diagnosis. The antigen tests (A2) could also be used for the diagnosis, but until now there are not many of them in the market.

The tests that detect exposition to the disease, known as “B category”, are usually the ones that detect antibodies in the blood, which have been produced by patient’s organism as a reaction to the virus infection. These test are commonly known as serologic tests, as they are applied to analyse the blood serum, and also popularly known as “fast or rapid tests”.

Every test is complementary. The first ones are reliable to know if a patient has the virus, independently of the symptoms. Nevertheless, they are not so reliable when it comes to know if a person has been exposed, since the sensitivity of these tests decreases a few weeks after the exposition. However, the second ones are not very efficient at the beginning of the exposition. The antibodies are not detectable within patient’s blood until 4 or 5 days later, even though they can detect high levels during the disease and even some time after the patient has recovered.

Our project wants to provide solutions for both diagnosis strategies with technologies that could be produced on a large scale and low cost basis. Hence, they could be used massively in possible future outbreaks of the disease.

It is possible thanks to a multidisciplinar team, with three CSIC centres involved: our Institute for Advanced Chemistry of Catalonia, the Institute of Microelectronics of Barcelona and the Institute for Materials Science of Aragón. Moreover, there are clinical groups from the Hospital del Mar of Barcelona and the Hospital Germans Trias i Pujol of Badalona which are also involved. During this period, we have started every necessary action to begin the broad part of the research. When necessary, some researchers have gone to the laboratories taking all necessary precautions.