[ad_1]
The new coronavirus has developed a number of disturbing mutations, leading to the emergence of several new variants around the world. Now, a new study is shedding light on how the virus mutates so easily and why these mutations help it “escape” the body’s immune response.
Researchers in the study found that SARS-CoV-2, the virus that causes COVID-19, often mutates by simply removing small pieces of its genetic code. Although the virus has its own “replay” mechanism that corrects errors during virus replication, a deletion will not show up on the reviewer’s radar.
“It’s devilishly smart,” study lead author Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh, told Live Science. “You cannot fix what is not there.”
In addition, for SARS-CoV-2, these deletions frequently appear in similar places on the genome, according to the study published Feb. 3 in the journal Science. These are sites where people’s antibodies bind to the virus and inactivate it. But because of these deletions, some antibodies cannot recognize the virus.
Duprex likened the deletions to a string of pearls where a pearl came out. It might not seem like a big deal, but for an antibody it’s “completely different,” he said. “These tiny little absences have a very big effect.”
Sneaky deletions
Duprex and his colleagues first noticed these deletions in a patient infected with the coronavirus for an unusually long time – 74 days. The patient had a weakened immune system, which prevented them from properly eliminating the virus. Over the course of the long infection, the coronavirus began to evolve by playing “cat and mouse” with the patient’s immune system, eventually developing deletions, the researchers said.
They wondered how common these deletions were. They used a database called GISAID to analyze some 150,000 genetic sequences of SARS-CoV-2 collected from samples around the world. And a pattern appeared. “These deletions have started to line up at very distinct sites,” said lead author Kevin McCarthy, assistant professor of molecular biology and molecular genetics at the University of Pittsburgh.
“We kept seeing them over and over and over again,” he said in SARS-CoV-2 samples taken from different parts of the world at different times. It appears that these virus strains independently developed these deletions due to “joint selective pressure,” the researchers wrote in their paper.
The researchers dubbed these sites “regions of recurrent deletion.” They noticed that these regions tended to occur at places on the peak protein of the virus where the antibodies bind in order to deactivate the virus. “This gave us the first clue that these deletions may have been leading to the ‘leak’ or evolution [of the virus] away from the binding antibodies, ”McCarthy said.
Predict new variants
The researchers began their project in the summer of 2020, when the coronavirus was not believed to be mutating significantly. But the deletions that popped up in their data said the opposite. In October 2020, they spotted a variant with these deletions that would later become known as the “UK variant” or B.1.1.7. This variant gained worldwide attention from December 2020, when it took off quickly in the UK.
“Our investigation of deletion variants captured the first representative of what would become the B.1.1.7 lineage,” the authors wrote. Their discovery underscores the importance of closely monitoring the evolution of the virus by tracking these deletions and other mutations.
“We have to develop the tools, and we have to step up our vigilance to seek out these things and track them… so that we can start to predict what’s going on,” McCarthy said.
Although the virus can mutate to escape certain antibodies, other antibodies can still bind effectively to the virus and inactivate it.
“Battling the virus in a number of different ways is how we’ve beaten the shapeshifter,” Duprex said in a statement. “Combinations of different antibodies [i.e. different monoclonal antibody treatments] … Different types of vaccines. If there is a crisis, we will want to have these safeguards. “
The results also show why it’s important to wear a mask and implement other measures to prevent the virus from spreading – the more people it infects, the more likely it is to replicate and potentially mutate.
“Anything we can do to reduce the number of reps … will save us some time,” Duprex said.
Originally posted on Live Science.
[ad_2]
Source link