What if the coronavirus remains in the body? We know this about chronic covid-19 – Health

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With millions of people recovering from covid-19, the question remains to what extent the virus is still hiding in apparently recovered patients. Is this a possible explanation for the persistent symptoms of Covid-19 in some?

University of Virginia Professor of Medicine, William Petri, studies infectious diseases and also cares for and examines infected patients. He explains what is known today about chronic or persistent Covid-19.

What is a chronic or persistent viral infection?

A chronic or persistent infection lasts for months or even years. Virus is constantly being produced during this period, albeit at low levels in many cases. These infections often occur in a so-called ‘privileged immunological site’.

What is a privileged immunological site?

There are a few immune-privileged places in the body that are less accessible to the immune system. Viruses are less easily eradicated because they are protected against the host’s immune response. These include the central nervous system, testes and eye. It is believed that the evolutionary advantage of such an immune-privileged region is that it protects a place like the brain from damage from inflammation that occurs when the immune system fights an infection.

An immune-privileged place is not only difficult to reach for the immune system, it also limits the production of proteins that increase inflammation. The reason is that while inflammation helps kill a pathogen, it can also damage an organ such as the eye, brain, or testicles. The result is an uncomfortable truce where inflammation is limited, but infection remains.

What is the difference between a latent infection and a persistent viral infection?

However, there is another way that a virus can hide in the body and reappear later: latency (latency).

Latent viral infection occurs when the virus is present in an infected cell, but is dormant and does not multiply. In a latent virus, the entire viral genome is present and infectious virus can be produced when the latency ends and the infection becomes active. The latent virus can thus be integrated into the human genome – like HIV, for example – or exist in the nucleus as a self-replicating piece of DNA, also called an episome.

Viruses latent in humans are difficult or even impossible for the immune system to eradicate.

A latent virus can be reactivated and produce infectious viruses. This can occur months to decades after the initial infection. Perhaps the best example of this is the chickenpox, which, although apparently eradicated by the immune system, can reactivate decades later and cause herpes zoster (shingles). Fortunately, chickenpox and shingles are now prevented by vaccination. Being infected with a virus that can cause a latent infection means that you are infected for the rest of your life.

How does a virus become a latent infection?

Herpes viruses are by far the most common viral infections causing latency.

It is a large family of viruses whose genetic material, or genome, is encoded by dna (and not rna like the new corona virus). Herpes viruses include not only herpes simplex viruses type 1 and 2 – which cause oral and genital herpes – but also chicken pox. Other herpes viruses, such as the Epstein Barr virus, the cause of glandular fever, and the cytomegalovirus can also develop after a period of latency.

Retroviruses are another common family of viruses that can be latent, but with a different mechanism than the herpes viruses. Retroviruses such as HIV, which can cause AIDS, can introduce a copy of their genome into human DNA. There, the virus can be in a latent state indefinitely. The virus genome is copied every time DNA is replicated and a cell divides.

Viruses latent in humans are difficult or even impossible for the immune system to eradicate. That’s because little or no viral protein production happens in the infected cell during the latent period, making the infection invisible to the immune system. Fortunately, coronaviruses do not form latent infections.

Could persistent symptoms after covid-19 result from viral persistence?

Covid-19 recovery is slow or incomplete in many individuals, with symptoms such as coughing, shortness of breath, and fatigue. It seems unlikely that these symptoms are due to viral persistence, since these symptoms are not from the privileged immunological sites.

In what places in the body could the new coronavirus persist after recovery of Covid-19?

Other locations where coronavirus has been detected are the placenta, the intestines, the blood and of course the respiratory tract. In women who receive covid-19 during pregnancy, the placenta develops defects in the mother’s blood vessels that feed the placenta. However, the significance of this for the health of the fetus has yet to be determined. The new coronavirus can infect the fetus through the placenta.

The new coronavirus also remains in the blood, nasal cavity and palate for up to a month or more after infection.

Like many things during this pandemic, what is unknown today is known tomorrow, so the main message is to stay alert and careful not to catch the infection or, worse, spread it to someone else.

Bron: The Conversation

University of Virginia Professor of Medicine, William Petri, studies infectious diseases and also cares for and examines infected patients. He explains what is known today about chronic or persistent covid-19. A chronic or persistent infection lasts for months or even years. Virus is constantly being produced during this period, albeit at low levels in many cases. Often these infections occur in what is called a “ privileged immunological site. ” There are a few immune-privileged sites in the body that are less accessible to the immune system. Viruses are less likely to be eradicated because they are protected from the host’s immune response. These include the central nervous system, testes and eye. The evolutionary advantage of such an immune-privileged region is believed to be that it protects a site such as the brain from damage from the inflammation that occurs when the immune system fights infection. An immune-privileged site is not only difficult to reach for it. immune system, it also limits the production of proteins that increase inflammation. The reason is that while inflammation helps kill a pathogen, it can also damage an organ such as the eye, brain, or testicles. The result is an uncomfortable truce in which inflammation is limited, but the infection remains, but there is another way a virus can hide in the body to resurface later: latency (latency). when the virus is present in an infected cell, but is dormant and does not multiply. In a latent virus, the entire viral genome is present and infectious virus can be produced when the latency ends and the infection becomes active. The latent virus can thus be integrated into the human genome – such as HIV – or exist in the nucleus as a self-replicating piece of DNA, also called an episome, a latent virus can be reactivated and produce infectious viruses. This can occur months to decades after the initial infection. Perhaps the best example of this is the chickenpox, which, although apparently eradicated by the immune system, can reactivate decades later and cause herpes zoster (shingles). Fortunately, chickenpox and shingles are now prevented by vaccination. Being infected with a virus that can cause a latent infection means that you are infected for the rest of your life. Herpes viruses are by far the most common viral infections that cause latency. It is a large family of viruses whose genetic material, or genome, is encoded by dna (and not rna like the new coronavirus). Herpes viruses include not only herpes simplex viruses type 1 and 2 – which cause oral and genital herpes – but also chicken pox. Other herpes viruses, such as the Epstein Barr virus, the cause of glandular fever, and the cytomegalovirus, can also develop after a period of latency. Retroviruses are another common family of viruses that may be latent, but with a different mechanism from the herpes viruses. Retroviruses such as HIV, which can cause AIDS, can introduce a copy of their genome into human DNA. There, the virus may be in a latent state indefinitely. The virus genome is copied every time DNA is replicated and a cell divides. Viruses latent in humans are difficult or even impossible for the immune system to eradicate. That’s because little or no viral protein production happens in the infected cell during the latent period, making the infection invisible to the immune system. Fortunately, coronaviruses do not form latent infections. Recovery from covid-19 is slow or incomplete in many individuals, with symptoms such as coughing, shortness of breath, and fatigue. It seems unlikely that these symptoms are due to viral persistence, as these symptoms do not originate from the privileged immunological sites.Other locations where coronavirus has been detected include the placenta, intestines, blood and of course the respiratory tract. In women who receive covid-19 during pregnancy, the placenta develops defects in the mother’s blood vessels that feed the placenta. However, the significance of this for the health of the fetus has yet to be determined. The new coronavirus can infect the fetus through the placenta. The new coronavirus also remains in the blood, nasal cavity and palate for up to a month or more after infection. Like many things during this pandemic, what is unknown today is known tomorrow , so the main message is to stay alert and careful not to catch the infection or, worse, spread it to someone else.

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