How Long Coronavirus stays Inside Human Body ?

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.

How Long Coronavirus stays Inside Human Body?

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 ?

DISCOVER MORE : DownToEarth Issues

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