How Long Coronavirus stays Inside Human Body ?

HEADLINES:

Does coronavirus linger in the body?

WHY IN NEWS:

What we know about how viruses in general hang on in the brain and testicles.

SYLLABUS COVERED: GS 3 : Science : Diseases

LEARNING:

For PRELIMS understand the chronic infections , causes and the concept of immune privileged sites.

For MAINS how does a Virus become Latent Infection ? Let us dive in !

ISSUE:

The mounting evidence suggests that SARS-CoV-2 can infect immune privileged sites and, from there, result in chronic persistent — but not latent — infections

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.

In many cases the reproduction rate of parasites is 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.

These include the central nervous system, the testes and the eye.

It is advantage of having an immune privileged region is that it protects a site like the brain, for example, from being damaged.
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.

A LATENT INFECTION VERSUS A PERSISTENT VIRAL INFECTION

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 a self-replicating piece of DNA called an episome.

A latent virus can reactivate and produce infectious viruses.

This can occur months to decades after the initial infection.

EXAMPLE

Chickenpox : which although seemingly eradicated by the immune system can reactivate and cause herpes zoster decades later.

To be infected with a virus capable of producing a latent infection is to be infected for the rest of your life.
The immune system cannot detect this cell as being infected.

Latent infection (left) is when a cell is infected and the virus has inserted its genetic code into our human DNA.

SOURCES:DownToEarth

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).
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 humans.

Since the virus genome is copied every time DNA is replicated and a cell divides.

IASbhai WINDUP:

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.
This makes the infection invisible to the immune system.

Fortunately coronaviruses do not establish a latent infection.

SOURCES:DownToEarth | How Long Coronavirus stays Inside Human Body ?

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How Long Coronavirus stays Inside Human Body ?