Metro

  • Written by William Petri, Professor of Medicine, University of Virginia

As millions of people[1] are recovering from COVID-19, an unanswered question is the extent to which the virus can “hide out” in seemingly recovered individuals. If it does, could this explain some of the lingering symptoms of COVID-19 or pose a risk for transmission of infection to others even after recovery?

I am a physician-scientist of infectious diseases[2] at the University of Virginia, where I care for patients with infections and conduct research on COVID-19. Here I will briefly review what is known today about chronic or persistent COVID-19.[3]

What is a chronic or persistent viral infection?

A chronic or persistent infection continues for months or even years, during which time virus is being continually produced, albeit in many cases at low levels. Frequently these infections occur in a so-called immune privileged site.

What is an immune privileged site?

There are a few 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 testes and the eye. It is thought that the evolutionary advantage[4] to having an immune privileged region is that it protects a site like the brain, for example, from being damaged by the inflammation that results when the immune system battles an infection.

An immune privileged site not only is difficult for the immune system to enter, it also limits 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 testes. The result is an uneasy truce where inflammation is limited but infection continues to fester[5].

A latent infection versus a persistent viral infection

But there is another way that a virus can hide in the body and reemerge later.

A latent viral infection occurs when the virus is present within an infected cell but dormant and not multiplying. In a latent virus, the entire viral genome is present, and infectious virus can be produced if latency ends and the infections becomes active. The latent virus may integrate into the human genome – as does HIV, for example – or exist in the nucleus as a self-replicating piece of DNA called an episome.

A latent virus can reactivate and produce infectious viruses, and this can occur months to decades after the initial infection. Perhaps the best example of this is chickenpox[6], which although seemingly eradicated by the immune system can reactivate and cause herpes zoster[7] decades later. Fortunately, chickenpox and zoster are now prevented by vaccination. To be infected with a virus capable of producing a latent infection is to be infected for the rest of your life.

Does coronavirus linger in the body? What we know about how viruses in general hang on in the brain and testicles Latent infection (left) is when a cell is infected and the virus has inserted its genetic code into our human DNA. The immune system cannot detect this cell as being infected. An HIV infection can shift from latent to active if the infected cell is producing new viruses. ttsz / Getty Images[8]

How does a virus become a latent infection?

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

This is a large family of viruses whose genetic material, or genome, is encoded by DNA (and not RNA such as the new coronavirus). Herpes viruses include not only herpes simplex viruses 1 and 2[9] – which cause oral and genital herpes – but also chickenpox[10]. Other herpes viruses, such as Epstein Barr virus, the cause of mononucleosis[11], and cytomegalovirus[12], which is a particular problem in immunodeficient individuals, can also emerge after latency.

Retroviruses[13] are another common family of viruses that establish latency but by a different mechanism than the herpes viruses. Retroviruses such as HIV, which causes AIDS, can insert a copy of their genome into the human DNA that is part of the human genome. There the virus can exist in a latent state indefinitely in the infected human since the virus genome is copied every time DNA is replicated and a cell divides[14].

Viruses that establish latency in humans are difficult or impossible for the immune system to eradicate. That is because during latency there can be little or no viral protein production in the infected cell, making the infection invisible to the immune system. Fortunately coronaviruses do not establish a latent infection[15].

Does coronavirus linger in the body? What we know about how viruses in general hang on in the brain and testicles Is it safe for a man to have sex after recovering from COVID-19? Andrey Zhuravlev / Getty Images[16]

Could you catch SARS-CoV-2 from a male sexual partner who has recovered from COVID-19?

In one small study, the new coronavirus has been detected in semen[17] in a quarter of patients during active infection and in a bit less than 10% of patients who apparently recovered. In this study, viral RNA was what was detected, and it is not yet known if this RNA was from still infectious or dead virus in the semen; and if alive whether the virus can be sexually transmitted. So many important questions remain unanswered.

Ebola is a very different virus from SARS-C0V-2 yet serves as an example of viral persistence in immune privileged sites. In some individuals, Ebola virus survives in immune privileged sites for months after resolution of the acute illness. Survivors of Ebola have been documented with persistent infections in the testes, eyes, placenta and central nervous system.

The WHO recommends for male Ebola survivors that semen be tested for virus every three months.[18] They also suggest that couples abstain from sex for 12 months after recovery or until their semen tests negative for Ebola twice. As noted above, we need to learn more about persistent new coronavirus infections before similar recommendations can be considered.

Could persistent symptoms after COVID-19 be due to viral persistence?

Recovery from COVID-19 is delayed or incomplete[19] in many individuals, with symptoms including cough, shortness of breath and fatigue. It seems unlikely that these constitutional symptoms are due to viral persistence as the symptoms are not coming from immune privileged sites.

Where else could the new coronavirus persist after recovery from COVID-19?

Other sites where coronavirus has been detected include the placenta, intestines, blood and of course the respiratory tract. In women who catch COVID-19 while pregnant, the placenta develops defects in the mother’s blood vessels supplying the placenta[20]. However, the significance of this on fetal health is yet to be determined.

[Deep knowledge, daily. Sign up for The Conversation’s newsletter[21].]

The new coronavirus can also infect the fetus via the placenta[22]. Finally, the new coronavirus is also present in the blood and the nasal cavity and palate for up to a month[23] or more after infection.

The mounting evidence suggests that SARS-CoV-2 can infect immune privileged sites and, from there, result in chronic persistent – but not latent – infections. It is too early to know the extent to which these persistent infections affect the health of an individual like the pregnant mother, for example, nor the extent to which they contribute to the spread of COVID-19.

Like many things in the pandemic, what is unknown today is known tomorrow, so stay tuned and be cautious so as not to catch the infection or, worse yet, spread it to someone else.

Authors: William Petri, Professor of Medicine, University of Virginia

Read more https://theconversation.com/does-coronavirus-linger-in-the-body-what-we-know-about-how-viruses-in-general-hang-on-in-the-brain-and-testicles-142878

Metropolitan republishes selected articles from The Conversation USA with permission

Visit The Conversation to see more

Entertainment News

A retrospective on Frasier, America’s sitcom set in Seattle

2020 marks the 27th anniversary of America’s popular TV show Frasier. The well-loved sitcom, which can be viewed in Australia on 10 Peach and streamed on Stan and Foxtel, had an 11-year run and ...

Polly Simmons - avatar Polly Simmons

BRANDYN CROSS: “If Money Talks (It Ain’t Sayin’ Much to Me)”

“If Money Talks (It Ain’t Sayin’ Much to Me)” Embracing an empowering “carpe diem” aesthetic ever since a tragic accident changed the trajectory of his life, the multi-talented- and autistic- ...

News Company - avatar News Company

Violin ReEnvisioned

Falling in love with music so young was more than transformative. Music became the lead sheet of my life; challenging me to navigate changes with grace, maintain a steady rhythmic groove, dynami...

Chelsey Green - avatar Chelsey Green

Kadda Sheekoff Win Best Urban Song For "All My Life"

Singer Kadda Sheekoff have emerged as the toast of the 2020 Songdew Pause&Play. Obviously, there are many composers who deserve the award more than Kadda Sheekoff, but the decision of the S...

Media Release - avatar Media Release

A Musical Journey: The Authentic Ted Cline

Ted Cline was born in 1962 as the 11th of 13 children.  His parents were hard-working tobacco share-croppers in Weston, Missouri. By the time he was eleven, he was sneaking downstairs to play his...

Ted Cline - avatar Ted Cline

Angela Predhomme - My Musical Journey

Determined to “make it” in the music industry as a songwriter, I meticulously crafted the best songs I could and pitched them to industry gatekeepers. “THIS one’s got to be IT,” I thought. But ala...

Angela Predhomme - avatar Angela Predhomme

GREYE: “So Far So Good”

“So Far So Good” After seven plus years firing up venues up and down the Atlantic Coast and throughout the Midwest to the breakneck tune of 90-110 annual shows, it’s definitely been jarring fo...

News Company - avatar News Company

The life and times of Wendy Moten

I never thought I would be in the music business, much less a recording artist. I never saw it coming. I thought I'd be a corporate attorney or something like that. Little did I know that anothe...

Wendy Moten - avatar Wendy Moten

CARY PARK “You Matter to Me”

“You Matter to Me” In any other time, Cary Park’s stunning new single “You Matter to Me” might be just another beautiful heartfelt love song, an outpouring of personal affection towards a cheri...

News Company - avatar News Company

Metropolitan Business News

MODEL/ACTOR THORN CASTILLO IS THE “NEW FACE” OF SCHICK STYLIST

In 2019, just as his multi-faceted career was taking off, Thorn Castillo heard Robert Downey Jr. offer a sage bit of advice during an interview on photographer/director Sam Jones’ acclaimed multi-...

News Company - avatar News Company

New Research Highlights Opportunities for Sports Betting

Revenue Stream for Sports’ Post-COVID-19 Recovery Strategies New Rochelle, NY, June 1, 2020— Twenty-four states have now legalized sports betting, with more states considering legalization la...

Len Stein - avatar Len Stein

How to make overseas transfers easier?

Mainstream banks can charge as much as $20 just to process a basic international money transfer. Fortunately, today people are not doomed to handling personal finances only through mainstream gl...

News Company - avatar News Company

The flourishing international market of fragrance and perfume

There is something special and unique about the art of fragrance. This is a big world and there are quite literally a lot of smells around at any given time. In fact, as one of the five human senses i...

News Company - avatar News Company

Impact of good marketing on sales

Sales and marketing are brothers as they go hand and in hand. The job of both of these departments is to generate revenue so that an organization can make money. A company that does not generate rev...

News Company - avatar News Company

7 effective tips for increasing sales in retail

It seems that retailers have drawn a difficult lot in the 21st century: competition from online retail is growing steadily. After all, Internet retailers can sell your products at significantly lowe...

News Company - avatar News Company

Holidays

5 COOL GADGETS TO CARRY FOR A SAFE TRIP

Are you planning to go on a trip? Possibly, you do not know what things are most necessary on a trip. In this article, we will guide you through some important tips. These tips help you to...

News Company - avatar News Company

New Baggage Regulations to Help Aussie Parents Travel with Infants

Travelling around the globe has never been easy, especially when infants tag along for the trip. One of the main issues that parents often have to deal with is the need to bring extra item...

News Company - avatar News Company

Maya Beach Opens to Tourists

Despite recent reports that Southern Thailand's famous Maya Beach will close for three months this year, in fact no decision to this effect has been made by Thai authorities. Phi Phi Nati...

Maevadi Rosenfeldt - avatar Maevadi Rosenfeldt