Viruses that can remain hidden in the body and cause problems after decades (and as for Covid)

Viruses that can remain hidden in the body and cause problems after decades (and as for Covid)

The process of invasion and replication takes several days, and if the immune system fails to cope with the problem, the condition becomes more serious and life-threatening.

Some viruses are able to integrate and "hide" in our genome.
Some viruses are able to integrate and “hide” in our genome.

If viruses can be identified by one characteristic, objectivity would be a good option. After all, its purpose is quite simple: to penetrate the cells of living beings and use them to create new copies of themselves that will repeat this process. Usually, the invasion and reproduction ritual lasts for several days, and if the immune system fails to cope with the problem, the condition becomes more serious and life-threatening.

But there is a group of viruses that go one step further.

Shortly after the primary infection, They manage to hide in any part of the body.

This phase can last for months, years or even decades and ends only then The defense cells stop working As expected.

Then the infection returns and causes health problems again.

And this group has several well-known representatives, starting with HIV, which causes AIDS, even herpes simplex 1 and 2, which cause ulcers in the corner of the mouth and in the genital area.

Herpes simplex 1 and 2 cause ulcers in the corner of the mouth and in the genital area
Herpes simplex 1 and 2 cause ulcers in the corner of the mouth and in the genital area

But, How do they manage to go unnoticed? And how do they emerge after so long? Could this be the case of SARS-CoV-2, which is responsible for Covid-19?

Basically, There are four ways In which the virus is hidden in the body.

The first of these is often used by the herpes family.

In addition to herpes simplex virus types 1 and 2, it is included Chickenpox and Epstein-Barr, which stands behind the “kiss disease”. Among others.

“They have DNA as genetic material and can stay in the nucleus of cells as a Appendix to our own genetic code“, Explains virologist Dezio Diamanti, from Israel Albert Einstein Hospital in Sao Paulo.

Here we must remember that DNA is the set of letters (known in science as nitrogenous bases) that make up the genome. They are “lined” with two threads, usually in a classic double spiral format.

“These viruses of the herpes family remain dormant for a long time, without multiplying very intensively. They are able to inhibit the internal protection of cells and Become “invisible” to the immune system“- adds a doctor who is also a consultant to the Brazilian Society of Infectious Diseases.

DNA is usually in the form of a double helix.
DNA is usually in the form of a double helix.

RNA viruses

The The second mechanism It is commonly used by other families: retroviruses such as HIV and HTLV.

It is important to note that this duo has not DNA but RNA.

In other words, yours Genetic information is organized in a simpler wayIn a single chain of nitrogenous base sequences.

Retroviruses They can merge with our genetic code.

This integration most commonly occurs in T cells and macrophages, two important parts of the immune system.

But, How do they accomplish this success? Are we talking about RNA viruses and are we based on DNA?

Both HIV and HTLV have an enzyme called reverse transcriptase.

And that means Can transform genetic code From the RNA to the DNA of these viruses.

By doing so they can Involved in the human genome And will remain hidden for a long time.

“This is a big challenge because we can not eliminate them even with available medicines,” explains Dr. Estevao Portella Nunes, Deputy Director of Clinical Services at the National Institute of Infectious Diseases (OSI) FioCruz. Rio de Janeiro.Janeiro.

In other words, the antiretroviral cocktail used in HIV-infected patients can even inhibit virus replication. However, If a person stops taking medication, There is a risk that HIV will become active again.

Long-term Covid is associated with inflammation
Long-term Covid is associated with inflammation

Altarpieces and other secrets

A third option for hiding some viruses is the so-called Immunoprotective sites.

These are areas of the body that the immune system cannot easily access, such as the testicles, eyes, and central nervous system (spinal cord and brain).

The action of defensive cells is limited in these areas To prevent the inflammatory process, This happens when they fight infection, damaging more sensitive structures such as nerves and the reproductive system.

If, on the one hand, it represents A form of self-defenseOn the other hand, it creates a kind of “altar” for some viruses to flourish for a while.

Found a paper published in recent years Zika and Ebola in sperm Patients, for example.

Immunologist Daniel Mucida, a professor at Rockefeller University in the US, says the fact that the virus is found in semen or other parts of the body does not necessarily mean that. Which is active and may cause problems in the future.

“The impact of this viral resistance is not yet clear,” he said.

And, as far as is known, the persistence of viruses in such an altar does not last so long.

Within a few months, even with the most limited access, The immune system can eventually eliminate it Invaders.

There is still a fourth group of viruses that can prolong their presence in the body, even in immunoprotected areas.

“This is a case of respiratory syncytial virus that can spread to the lungs and is associated with chronic inflammation, especially in children and Chikungunya virusWhich stays in the muscles and joints, ”says Carolina Lucas, an immunologist at Yale University School of Medicine in the United States.

Scientists are still studying why this happens in some patients (and not in some patients).

Ebola has already been detected in patients's eyes and testicles
Ebola has already been detected in patients’s eyes and testicles

Immune barrier

While it may seem like all these viruses are dormant and no longer a cause for concern, some of them “wake up” after a few years (or decades).

“When the immune system makes a mistake for any reason, These pathogens may re-emerge And causes problems, “Diamanti explains.

This “error” varies from infection to infection.

In the case of herpes simplex, if an infected person spends many hours in the sun or is exposed to A very stressful period in your lifeThis may be enough to make the lesions appear.

In other situations, The body’s own natural aging Leaves room for some infectious agents to wake up.

A classic example of this is varicella-zoster, a virus that causes chickenpox (usually in childhood) and has been hidden in the body for decades.

Later, after 50 or 60 years, this causative agent may reappear and cause a condition called shingles.

Today, a vaccine is even prescribed for these elderly people.

And, of course, there are a few Other conditions that inhibit the functioning of the immune system And may become a possibility of viruses.

“Includes Serious Accidents and Injuries, Serious Operations, Transplants, “Tumors, pharmacological treatment and other serious infections,” Diament lists.

In such cases, doctors are already monitoring them and can provide treatment to reduce the damage.

Finally, we must also remember that some pathogens are associated with diseases that are not always associated with the initial manifestations of the infection.

For some, this is the case Hepatitis virus, Which can lead to liver cancer, HPV, which stands behind several types of tumors.

Or also from Epstein-BarrWhich has recently been linked to multiple sclerosis.

Shingles is characterized by reactivation of the chickenpox virus.
Shingles is characterized by reactivation of the chickenpox virus.

And Kovid?

Given such a diversity of viruses, can SARS-CoV-2, which causes Covid-19, persist after the initial infection?

The experts were consulted by BBC News Brazil They are unlikely to have or develop these abilities.

“SARS-CoV-2 is an RNA virus that does not have the reverse transcriptase enzyme that HIV does, so it cannot be integrated into our genome,” explains Carlos Menck, a molecular biologist at the Institute of Biomedical Sciences’ Department of Microbiology. University of S პo Paulo (ICB-USP).

Რ as Lacks DNA in its constitution; As is the case with viruses of the herpes family, which prevents their long-term resistance in the cell.

“And the cases that we see now, of people who still have covidium, happen because they became infected with the coronavirus for the second time and not because it was hidden in their body for months,” explains the specialist.

“If we find anything else about the Covid virus, it will be a big surprise for us.”

Zika, Dengue, and Chikungunya viruses are transmitted by mosquitoes;  These viruses are known as arboviruses
Zika, Dengue, and Chikungunya viruses are transmitted by mosquitoes; These viruses are known as arboviruses

But, How to explain cases of prolonged Covid, Which individuals have discomfort for months, even after recovering from initial discomfort?

Diamond explains that this phenomenon seems to be more related to the immune system response to the invasion of the corovirus.

“In some patients, Covid causes real damage that can last for months and manifest itself Fatigue, difficulty concentrating, loss of smell… “

“It seems to be the result of an inflammatory process that occurs in the first days of infection. In some cases, The immune system reacts violentlyAnd the effect of this can be prolonged, “- explains the doctor.

However, Lucas and Mucida say that in these cases the persistence of some viral components such as Protein and RNA fragmentsIn the body.

“There is evidence that points to both sides, including the observation of viral RNA in regions such as the intestine for a long time,” they said.

Whether or not these small virus fragments remain Be able to maintain vigilance of the immune system And cause harm for weeks or months, or if they are just a conclusion that has no practical impact on human health.

But as Portela Nunes from Fiocruz points out, in the case of Covid-19, we already have at least one good news: “Vaccination seems to protect or minimize this discomfort in the long run.”

By Andre Biernat

BBC World

Source: La Nacion

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