Certain strains of the virus can remain in the human body for many years after the initial infection. The most vulnerable areas are the eyes; Brain; testes and placenta whereInflammation can be deadly. However, these areas, known as "privileged immune sites", have mechanisms that protect tissues from immune-mediated damage. The brain is vital for survival, so a balance between defense against pathogens and harmful inflammatory responses is needed. on alearnPerformed in Germany, it was found that the antibodies we produce respond to itCOVID 19do not destroy the virus and make it similar to HIV. William Petri examines what we know about the virus and its ability to spread from person to person. This article originally appeared onThe conversation.—Claire Badenhorst
Does the corona virus stay in the body? What We Know About How Viruses Usually Take Home in the Brain and Testicles
By Guilherme Petri*
Semillion peopleRecovery from Covid-19 is an unanswered question about the extent to which the virus can "hide" in apparently recovered individuals. If so, could this explain some of the persistent symptoms of Covid-19 or pose a risk of passing the infection on to others even after recovery?
I am onephysician-scientistin Infectious Diseases at the University of Virginia, where I care for patients with infections and do research on Covid-19. Here I will briefly summarize what is known todayChronic or persistent Covid-19.
What is chronic or persistent viral infection?
Chronic or persistent infection lasts for months or even years, during which time the virus is continually being produced, albeit at low levels in many cases. These infections usually occur in a location called an immune privilege.
What is a Privileged Immune Site?
There are some places in the body that are less accessible to the immune system and where it is difficult to eradicate all viral infections. These include the central nervous system, the testicles and the eye. It is believed that theevolutionary advantageThe existence of an immune-privileged region is that it protects a place, such as the brain, from damage caused by the inflammation that occurs when the immune system fights an infection.
Not only is it an immune-privileged site that is difficult for the immune system to access, it also restricts proteins that increase inflammation. That's because while inflammation helps kill a pathogen, it can also damage an organ, such as the eye, brain, or testicles. The result is an uneasy truce.Inflammation is limited, but the infection continues to fester.
A latent infection versus a persistent viral infection
But there is another way for a virus to hide in the body and reappear later.
Latent viral infection occurs when the virus is present in an infected cell but is dormant and not multiplying. The entire viral genome is present in a latent virus, and an infectious virus can be produced when latency ends and infections become active. The latent virus can integrate into the human genome – like HIV, for example – or exist in the cell's nucleus as a self-replicating piece of DNA called an episome.
A latent virus can reactivate and produce infectious virus, and this can happen months to decades after the initial infection. Perhaps the best example of this ischickenpox, which, although apparently eradicated by the immune system, can be reactivated andcause herpes zosterdecades later. Fortunately, chickenpox and zoster are now preventable by vaccination. Being infected with a virus that can produce latent infection means being infected for life.
How does a virus become a latent infection?
Herpesviruses are by far the most common viral infections that cause latency.
This is a large family of viruses whose genetic material, or genome, is encoded by DNA (rather than RNA like the novel coronavirus). Herpesviruses include not onlyHerpes simplex virus 1 and 2– which cause oral and genital herpes – but alsochickenpox. Other herpesviruses, such as the Epstein-Barr virus, are the causemononucleosis, ECytomegalovirus, a particular problem in immunocompromised individuals, can also occur after latency.
retrovirusare another common family of viruses that produce latency, but by a different mechanism than herpesviruses. Retroviruses like HIV, which cause AIDS, can insert a copy of their genome into human DNA, which is part of the human genome. There, the virus can exist indefinitely in a latent state in the infected human due to the presence of the virus genome.copiedEvery time DNA is replicated and a cell divides.
Viruses that accumulate latency in humans are difficult or impossible for the immune system to eradicate. This is because, during the latency period, there may be little or no production of viral proteins in the infected cell, making the infection invisible to the immune system. fortunatelycoronavirusdetect no latent infection.
Could you catch SARS-CoV-2 from a male sexual partner who has recovered from Covid-19?
The new corona virus was examined in a small studydetected in semenin a quarter of patients during an active infection and in just under 10% of patients who appear to have recovered. Viral RNA was detected in this study and it is still unknown whether this RNA is from still infectious or dead virus in semen; and if alive, whether the virus is sexually transmitted. So many important questions remain unanswered.
Ebola is a very different virus from SARS-C0V-2, but it serves as an example of viral persistence in immunoprivileged sites. In some individuals, the Ebola virus survives in immune-privileged sites for months after the acute illness resolves. Ebola survivors have been documented with persistent infections in the testicles, eyes, placenta and central nervous system.
WHO recommends this seed for male Ebola survivorsbe testedevery three months for viruses. They also suggest couples abstain from sex for 12 months after recovery or until their semen has tested negative for Ebola twice. As mentioned above, we need to learn more about ongoing novel coronavirus infections before similar recommendations can be considered.
Could persistent symptoms after Covid-19 be due to viral persistence?
lazerRecovery from Covid-19 is delayed or incomplete in many individuals, with symptoms such as coughing, shortness of breath and fatigue. It seems unlikely that these constitutional symptoms are due to viral persistence, as the symptoms do not come from immunoprivileged sites.
After recovering from Covid-19, where else could the new coronavirus persist?
Other places where the coronavirus has been detected are the placenta, intestines, blood and, of course, the respiratory tract. In women who contract Covid-19 during pregnancy, the placenta developsdefectsin the mother's blood vessels that supply the placenta. However, the relevance of this to fetal health has yet to be determined.
The new corona virus can alsoinfect the fetusthrough the placenta. After all, it is also present in blood andnasal cavity and palateup to a month or more after infection.
Growing evidence suggests that SARS-CoV-2 can infect immunologically privileged sites, and from there lead to persistent, but not latent, chronic infections. It is still too early to know to what extent these persistent infections affect the health of a person as a pregnant mother and to what extent they contribute to the spread of Covid-19.
As with many things in the pandemic, what you don't know today you know tomorrow, so be aware and be careful to avoid catching the infection or, worse, spreading it to someone else.
- William of Peter, professor of medicine,University of Virginia. This article is republished byThe conversationunder a Creative Commons license. read thisoriginal article.
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