The new coronavirus has developed a number worrying mutations, leading to several new variants appearing around the world. A new study sheds light on how the virus mutates so easily and why these mutations help “escape” the body’s immune response.
The researchers found that SARS-CoV-2, the virus that causes COVID-19, often mutates by removing only small pieces of its genetic code. Although the virus has its own “proofreading” mechanism that corrects errors if the virus repeats, a removal will not appear on the proofreader’s radar.
“It’s devilishly clever,” senior author Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh, told WordsSideKick. “You can not fix what is not there.”
What’s more, for SARS-CoV-2, these deletions occur frequently in similar places in the genome, according to the study, published Feb. 3 in the journal. Science. These are sites where people’s antibodies can bind to and deactivate the virus. But because of this deletion, sure antibodies cannot recognize the virus.
Duprex compared the scrapings to a string of beads where one bead is jumped out. It may not seem like a big deal, but for an antibody it is ‘completely different’, he said. “These tiny little absences have a big, big effect.”
Sneaky removals
Duprex and his colleagues first noticed this deletion in a patient who had been infected with the coronavirus for an extraordinarily long time – 74 days. The patient has a weakened immune system, which prevented them from clearing the virus properly. During the prolonged infection, the coronavirus began to develop while playing ‘cat and mouse’ with the patient Immune systemeventually developed the removal, the researchers said.
They wondered how common such scrapings were. They use a database called GISAID to analyze approximately 150,000 genetic sequences of SARS-CoV-2 collected from samples around the world. And a pattern arose. “These scraps are starting to connect in many different areas,” said lead study author Kevin McCarthy, assistant professor of molecular biology and molecular genetics at the University of Pittsburgh.
“We’ve seen them over and over again,” in SARS-CoV-2 samples collected from different parts of the world at different times, he said. It appears that these virus strains are developing these removals independently due to a “general selective pressure”, the researchers wrote in their paper.
The researchers called these sites ‘repetitive removal regions’. They noted that these regions tend to occur on the viruses ear protein where antibodies bind to eliminate the virus. ‘It gave us the first idea that this deletion might lead to the’ escape ‘or the evolution [of the virus] away from the binding antibodies, ‘McCarthy said.
Predict new variants
The researchers started their project in the summer of 2020 when the coronavirus was not mutated in a significant way. But the scraps that appeared in their data said otherwise. In October 2020, they spotted a variant with these deletions that later than the “British variant, “or B.1.1.7. This variant received worldwide attention from December 2020, when it rose rapidly in the United Kingdom.
“Our survey for removal of variants captured the first representative of what would become the B.1.1.7 generation,” the authors wrote. Their finding underscores the importance of closely monitoring the evolution of the virus by detecting these deletions and other mutations.
“We need to develop the tools, and we need to strengthen our vigilance to look for these things and follow them … so we can start predicting what’s going on,” McCarthy said.
Although the virus can mutate to evade some antibodies, other antibodies can still bind and inactivate the virus effectively.
“Checking the virus in different ways is how we defeat the shape shifter,” 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 want the backup. ‘
The findings also show why it is important to wear a mask and take other measures to prevent the virus from spreading. The more people it infects, the more likely it is to recur and possibly mutate.
“Anything we can do to dampen the number of times it repeats … will buy us some time,” Duprex said.
Originally published on Live Science.