Have you been in direct contact with people who are sick with Covid-19 and were you never infected? Did you have PCR or immunological tests and they came out negative?If your answer is yes, you could be one of the rare people in the world who has genetic resistance to SARS-Cov-2, the virus that causes Covid-19.
And if you are, you could have “very valuable” information on how to prevent this disease that has caused more than five million deaths in the world.That is why a group of scientists from 10 countries is conducting a search to find these people resistant to SARS-Cov-2.
The researchers announced it in the journal Nature and since then they have recruited more than 500 people to undergo tests and verify if they are carriers of this genetic resistance.
“We are looking for members of a family, a married couple, for example, in which one was critically ill and the other cared for him, without acquiring the infection at any time,” Sara Espinosa, from the National Institute of Pediatrics, explains from Mexico.
“Or it could be someone from the health personnel, such as a doctor who was exposed caring for sick and positive patients and has never had the infection,” adds the doctor, who coordinates in that country the so-called International Consortium for the Human Genetic Study of Covid.
“In these cases we could be talking about a patient who is possibly resistant. That is, a person who has some mechanism in their genes by which the virus cannot cause the infectious process”. The “ideal” candidate, the researchers explain, is someone who has been repeatedly exposed to the virus and was never infected.
This person must have had negative PCR test results after exposure to the virus.And once you have an antibody test, it must be negative and show that the person did not develop antibodies against the virus because even though they were exposed to the virus they never became infected.
Resistant, not asymptomatic
“The resistant person had to have been in close contact with the infected person and not have had symptoms, but we must also confirm that the virus did not confer infection with a negative PCR test and a negative immunological antibody test,” explains Dr. Espinosa .
We now know that many people can become infected with the virus and not develop symptoms of the disease.But the researchers stress that these symptom-free people are not necessarily resistant to SARS-Cov-2, and they can carry the virus and spread it to other people.
“An asymptomatic person can be infected, have the virus and pass it on to other people,” explains immunologist Evangelos Andreakos, from the Athens Biomedical Research Foundation and who is also part of the Covid Human Genetic Study Consortium (COVIDHGE).
“The biological process of an asymptomatic patient is different and we are not looking for these people for this study.” “The category we are looking for is resistant people who do not get infected with the virus. In other words, although the virus may be in contact with the respiratory tract of this person, it cannot enter the cells or replicate within them”, explains the researcher.
The introduction of SARS-Cov-2 into populations around the world has allowed scientists to study vast differences in the virus’s infection processes, ranging from asymptomatic infections to life-threatening infections.
Since December 2019, when the virus was first detected, knowledge about the life-threatening Covid-19 disease and the genetic susceptibility that makes some people sicker than others has been on the rise.
However, very little is still known about the genetic basis for resistance to SARS-Cov-2. Scientists point out that this resistance, although rare, exists, because it has already been seen with other infectious diseases.
“We think that this resistance is very rare because that is what we have seen with other infectious diseases. We have seen cases of individuals with genetic variants that have made them resistant to HIV infection,”says Dr. Andreakos.“And we also have precedents for resistance to malaria and sickle cell anemia,” adds the researcher.
Researchers are conducting DNA analysis from volunteers with the goal of detecting regions that are different and comparing them to individuals who have been infected with the virus. The ultimate goal, the researchers say, is to be able to develop a therapy or treatment to prevent SARS-Cov-2 infection.
“The primary objective is to understand and know the mechanism by which some genetic change does not lead to the infectious process,” Dr. Sara Espinosa says. “And that knowledge can lead to finding drugs that are effective against SARS-Cov-2.””Because until today the drugs we have are to reduce the complications of the disease, but we do not have drugs against the microorganism as such.””And this research also aims to help find those drugs.”
The researchers say that identifying these people resistant to SARS-Cov-2 is “a huge task”, but they are confident that they will find them.“We know that there are a number of people who possibly have this immunity, this genetic change that confers resistance. We already have around 500 people recruited and genetic studies are already being carried out,”says Sara Espinosa.
“The search is not easy, but it is very important and even if we identify a few people they can provide a lot of information and very valuable. And that is why this effort is being made around the world”, she added. For Latin America, in addition to Mexico, the Covid Human Genetic Study is also being carried out in Colombia and Brazil.