Why in news?
- A mixture of three quasi-subspecies of SARS-CoV-2 is in circulation in India, the Indian Council of Medical Research (ICMR) said on 31st March 2020.
- These imported variants showed no differences from how they behaved in the place of origin.
- Scientists are yet to classify a SARS-Cov-2 variant as an Indian strain.
- India’s COVID-19 cases were mainly from people with travel history and their immediate contacts, which is to say that this virus was brought in from outside.
- ICMR is not seeing any variation from what is being seen on how this strain is behaving around the world. So there is no difference in its severity.
- However, in a large country like India, it’s difficult to predict an accurate trend about the progression of COVID-19 because we still don’t have enough time gap between the upswing of cases.
- The progression in terms of cases could not be compared with any other country as of now and people should be looking at the risk of exposure and adherence to physical distancing.
- Availability of testing kits was still an issue, and masks should not be used indiscriminately.
- India would be able to make indigenous diagnostic kits within the next month or two.
Virus and Strains of Viruses Explained
What is a virus?
A virus is a very simple thing – a coat of protein wrapped around some genetic code (DNA or RNA). It’s not a cell and it’s not living.
Hijacking a host cell
- A virus needs a host cell to be able to replicate itself. Once inside the host cell, it takes over.
- The cell is reprogrammed to produce the virus instead of doing what it was designed to do before.
- The virus is replicated thousands and thousands of times within that cell.
- Eventually, the cell bursts open and the multitude of viruses move around the body infecting other cells. This can happen within a few hours.
Mutation and Strains
- Mutation is when something changes as it is replicating. Viruses survive through mutation.
- This is a random act, rather than a deliberate act of survival.
- Some of the ways that viruses replicate are quite sloppy compared to the cells in our bodies.
- Our cells have special enzymes that make sure that a new cell has copied the gene sequence perfectly, but a virus is not so exact. The host cell (under instruction from the genetic material of the virus) produces thousands of copies of the virus, but they are often not going to be 100% exact.
- A slight mutation such as this with a virus means our immune system might not recognise it.
- That means the mutated virus copy can infect a new cell making another 50,000 copies of the new mutation without our immune system trying to stop it. The mutation results in a new strain of virus.
- You can have lots of strains (slight variations) of the same virus. Some viruses are sloppier than others when replicating and have many mutations. HIV (human immunodeficiency virus) is an example of this.
- Viruses like Influenza (flu) and rotavirus produce many different strains. They do this in a slightly different way from mutation.
- These viruses can make reassortant strains, meaning the strain is produced from the genetic material from two or more similar viruses.
- This happens when the gene material is chopped up in little pieces (rather than being in one long piece as with other viruses).
- Say you caught two different strains of the flu at once from two different people. A cell in your body could get infected with these two different strains. The strains can jumble up within the host cell and mix and match their little pieces of genetic material to create a new, dramatically different strain.
- This is how a flu pandemic occurs.
- The reassortant can spread quickly.
- Nobody’s immune system recognises the new virus strain so it is able to spread rapidly.