How virus variants evolve

"Viruses mutate as they replicate their DNA and produce a large number of new variants, and Darwin's law dominates at this point

The problem of natural selection

It occurred to Charles Darwin that the evolution of life forms occurs through a simple process of natural selection

The same goes for viruses, but they have certain peculiarities

"Most mutations are harmful to the virus and disappear quickly," explained Prof Albert

Two different viruses can also merge, and although this recombination is uncommon, it can lead to a huge evolutionary leap

multiple ways of dissemination

Viral success is defined by spreading

Viruses can increase their inherent ability to spread in a number of ways, such as by more efficiently binding to receptors on the surface of host cells and entering cells, producing more viral particles per cell, or leaving our cells faster or body

Virus variants can coexist—sometimes in the same host

But they can also cancel each other out

As expected, the new coronavirus variants are all more contagious

surprising variant

Ben Murrel, a researcher at the Department of Molecular and Cell Biology at Karolinska Institutet, said: "In the early days of the pandemic, it was widely believed that the relatively low mutation rate of SARS-CoV-2 meant that we didn't have to worry about it diversifying rapidly.

Coronaviruses mutate when base pairs in the RNA sequence are randomly deleted, added or replaced

The virus was almost completely unchanged for the first few months

"We don't fully understand why this is happening," Dr Murrel said

It started with alpha and beta variants discovered by British and South African scientists

Many believe the next problematic variant could be a descendant of Alpha, the most contagious of the three viruses

Next up is another surprise - Omicron
.
It is also completely unrelated to previous SARS-CoV-2 variants, but spreads extremely rapidly and has more than 30 new mutations in the spike protein

Laboratories around the world are monitoring the facts about virus surveillance
.
In Sweden, where public health agencies are tracking virus variants and collecting sequencing data from different laboratories, including clinical laboratories at seven university hospitals, SciLifeLab and the National Pandemic Center at Karolinska Institutet, about 70% of Sequencing happens in these labs
.

Unknown Omicron Background

Scientists don't know how Omicron accumulated so many mutations before it was discovered in South Africa

"One possible explanation is that it evolved in an immunocompromised patient who had been carrying the infection for a long time," Dr.
Murrel said
.
"Continued replication under the influence of the immune system will be able to explain many of the mutations we see in Omicron
.
"

Another possibility is that SARS-CoV-2 jumped back to another species, mutated, and then jumped back to humans

Researchers aren't entirely sure why Omicron spread so quickly
.
One theory is that the variant enters cells differently

Viruses use it to stab proteins into cells
.
But first, the spines need to be cleaved in the host cell by an enzyme called furin
.
However, there is another route into the cell through organelles called endosomes, a process that is more efficient if the protein is not cleaved

The high heritability of the Delta variant may be related to the higher cleavage ability of its spike protein
.
When Omicron came along, many scientists thought it used the same mechanism, but better

"But now we know that Omicron behaves differently," said Dr.
Murrel
.
"Spike is cleaved to a lesser extent, and it utilizes the endosome entry pathway more efficiently, but we don't yet know how
.
"

Avoid neutralizing antibodies

Part of the explanation is that it also sneaks beyond the immunity built up against earlier variants or vaccines based on the original variant protein

Dr.
Murrell's research team, in collaboration with Professor Albert, successfully cloned Omicron's spike protein from blood samples from patients suspected of Omicron
.
Their findings suggest that neutralizing antibodies (which prevent the virus from entering cells) are less effective against omicron than the original SARS-CoV-2 variant
.

He continued: "Omicron does a good job of avoiding neutralizing antibodies
.
That means you may be more susceptible to infection
.
"

However, the antibody response was not as bad as most expected
.
Some people have antibodies that also work against omicron, especially if they were previously infected and then vaccinated

"Subsequent studies from other laboratories have shown that a third dose of the boosted vaccine achieves a similar effect, although the vaccine still uses the peak of the original founding variant," Dr.
Murrel said
.