SARS-CoV-2- Why is it different this time?

COVID 19 disease, caused by human coronavirus SARS-CoV-2, has taken a toll on more than 200 nations worldwide. As on April 18,2020, globally more than 2.2 M people were battling for life. (John Hopkins Corona Virus Resource Centre).

The fact that only a little is known about the epidemiology and etiology of SARS-COV-2 combined with ill-preparedness of countries to contain it, led to the rapid rise of infections and mortality rates. What started in Wuhan city of China in December 2019, quickly turned side to makes Europe and USA, the worst affected zones.

Coronavirus is not a new name!

Coronavirus is a large family of viruses which are characterized by presence of “crown” of protein on their surface. These proteins help the virus to attach itself to the host cell surface proteins.

Human Coronavirus (HCoV) have been identified since 1960s. Four common HCoVs – NL63, HKU1, 229E and OC43, cause about 30% of the respiratory illness in humans. These are mild infections and easily treatable.

However, three types,

  • MERS-CoV (the beta coronavirus that causes Middle East Respiratory Syndrome, or MERS)
  • SARS-CoV (the beta coronavirus that causes severe acute respiratory syndrome, or SARS)
  • SARS-CoV-2 (the novel coronavirus that causes coronavirus disease 2019, or COVID-19)

are the dangerous ones.

Molecular structure

Coronaviruses are spherical particles with bulbous surface projections. The S-protein (spike protein) protrudes out of the cell membrane and gives the characteristic ”crown” shape to the virus. E protein and HE-protein are also present in the cell membrane which is internally lined by lipid bilayer.

SARS-Cov-2 structure
Adapted from – Scientific Illustrations

 

Inside the virus, is the positive sense, single stranded RNA genome. The genome size is around 30kb. All the structural genes for S, E, M and N and ORF regions are located.

SARS_Cov-2 genome
Adapted from- LSBio

 

The virus attaches itself to the host cell receptors using the S proteins and ‘hijacks’ the DNA replication and translational machinery of the host cell. It then produces a large of virus particles and then kill the host cell to release millions of virus copies.

SARS-CoV-2 replication cycle
Adapted from – faculty of Pharmaceutical Medicine

 

Why SARS- CoV-2 is different?

Ever since, the Covid-19 pandemic broke out in January 2019, scientists have been working to understand the genetic structure of SARS-CoV-2. Thanks to global developments in gene sequencing technology, it was not long before first complete sequence of SARS-COV-2 was available few days after its appearance.

As the virus spread, so does our understanding that the virus is highly prone to mutations and may develop new strains in new geographic conditions.

One of the early research published in China showed that SARS-COV-2 genome is 89% similar to SARS-CoV found in bats.

Another research demonstrated that the S protein on SARS-COV-2 is similar to SARS-Cov. It interacts with Angiotensin converting Enzyme 2 (ACE2) receptors in the host cell facilitating the entry of virus into the host cells. However, S protein of SARS-COV2 is longer than that of SARS cov and the Receptor Binding Domain (RBD) of SARS-Cov-2 is the hypervariable region of its genome and different from SARS-Cov. This RBD of SARS-Cov2 seems to be more effective in interacting with ACE2 domain on human cells.  It could explain the high spreading rate of SARS-Cov2.

Whether, the virus came from lab or viral natural mutation in bats via an intermediate host, SARS-CoV2 has proven to a challenge to medical science. No matter how ready we claimed to fight a global pandemic, this virus has thrashed all those claims.

In a span of few days, the virus spread globally and forced millions of people to get locked in their homes. Economies have shut down and millions job lost.

If we can learn anything from this pandemic, is that, medical science and research to save our country needs to be prioritized. Just like countries are spending billions on bombs, they need to start thinking about taking care of the healthcare sector to make them ready to fight a global pandemic.

Nature will not give any alarm before launching any such event. Event will just occur randomly and we will find ourselves at the our feet. No God, No religious leaders or any other act of faith in spirituality is going to save us from this virus. It’s the healthcare workers and medical science!

We should Stay at Home and Stay safe and cooperate with our government and healthcare workers who are fighting day and night to save us.

Reference:

(https://www.europeanreview.org/wp/wp-content/uploads/2781-2783.pdf)

https://www.nature.com/articles/s41423-020-0400-4)

https://www.ncbi.nlm.nih.gov/pubmed/31967327

Share this article:

Leave a Reply

Your email address will not be published. Required fields are marked *