Why biological viruses mutate so fast ?

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When the pandemic covid-19 started in 2019 viruses became the talk of the headlines. One of the most discussed thing about covid-19 virus was about its mutating capacity, currently various mutant variants of the virus can be found around the world, the most deadly which is thought to be the Brazil version of the virus. Here we will discuss about mutation, it’s properties and how it works.

What is a virus ?

A virus is a microscopic pseudo organism (considered dead when outside a living body) usually having parasitic behaviour that cannot live and reproduce outside a host body.

Genetic material of viruses are either DNA or RNA, surrounded by a protective covering called capsid made up of proteins.

What is mutation ?

Mutations are changes that occur in the RNA or DNA of a living organism or of a virus. They are the alterations in the genetic material ie. genome of the living creatures.

Mutations can be both natural that occur of its own or can also be caused of non-natural causes such as exposure to high energy radiations like gamma rays or x-rays.

As mutations are random changes almost all of them are destructive in nature, very few mutations are beneficial in certain conditions and environment, and they may or may not be heriditery.

A large group of viruses that have the same set or type of mutations are called as variants. The speed of mutation of viruses depends upon how widely the virus is spreading in the population.

Difference between DNA and RNA viruses

In genetics strands are polymers of deoxynucleoside monophosphates that are together linked by phosphodiester bonds, DNA viruses are double stranded whereas most of the RNA viruses are single stranded.

DNA is a complex structure as compared to RNA, presence of deoxyribose sugar in DNA makes it more stable than RNA containing ribose sugar.

RNA viruses, like the flu or covid-19, are more prone to changes and mutations compared with DNA viruses.

RNA viruses have higher chances to infect new species because of their shorter generation times and faster evolutionary rates.

Hiv is a RNA virus

Why high mutation rates in viruses ?

If you compare viruses with high level organisms like bacteria, protozoa or even human beings, the rate of mutation in viruses are very much high.

For high rates of mutation first we need to understand how viruses replicates, unlike bacteria that reproduce by dividing itself, viruses need a host body for its replication. Viruses hijack cells of the host body and changes the host’s cell biochemical characteristics, such that the host’s cells starts making the duplicates of the virus, so it’s the host’s cells thats replicating the virus not the virus itself.

So once a virus gets into our body it lay holds onto our cells. The virus’s DNA or RNA then enters out cells, as the genetic code is injected into the host’s cells it starts working according to the virus’s information given by the DNA or RNA.

One thing virus is bad at is passing onto genes ie. producing a exact copy of itself with same characteristic, due to which when host’s cells starts manufacturing the virus, the replicated viruses undergoes random copying errors, and these random errors is nothing but a mutation.

So the reason for viruses fast mutation is nothing but the half random genetic informations that viruses put into the host’s cells manufacturing unit. So it can be interpreted that if viruses would have replicated of their own like processes of cell division followed by other organisms like amoeba then they have produced exact copies of themselves and their mutation rates would have been much lower.

Is mutating virus dangerous ?

As we have discussed random and frequently occurring mutations are totally normal for viruses, it’s a natural process, means virus does not forcefully wants mutations it just happens in the flow of replication.

It can also be understood as the mutations are mostly random it may or may not favour the virus in most of the cases it weakens the virus.

The one type of mutations of the virus that is widely spread is called a variant or a strain of the virus.


Mutations in viruses are inevitable, they may or may not favour the virus because most of the mutations are just random copying errors by the host’s cells.

More widely the virus is spread in the population more will be the mutation rate.

Although many of these mutations are not dangerous then also vaccines needed to be updated every year to overcome any potential strain.

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