THE ASAHI SHIMBUN
December 13, 2021 at 18:35 JST
The Delta variant of the novel coronavirus (Provided by the National Institute of Infectious Diseases)
A certain mutation in the COVID-19 Delta variant causes infected cells to form disruptive chunks in the lungs and leads to more serious symptoms of the disease, a research team said.
If the cells in the chunks die, the lung tissues can become exposed to potentially severe damage, according to the researchers from the University of Tokyo’s Institute of Medical Science and other experts.
They said the increased health danger is likely caused by the P681R mutation, a hallmark of the Delta variant, which occurs in the spike protein, the area of the virus that infects human cells.
“This study, focusing on the P681R mutation, explains at least partly why the Delta variant causes more serious symptoms,” said Kei Sato, an associate professor at the institute who leads the research team. “It is possible that the virus having this mutation likely causes serious conditions, which means we should be wary of it.”
The team’s findings were published in the science journal Nature.
The team prepared cells for their experiment and infected them with the Delta variant. These cells stuck together and formed chunks that were 3.6 times larger on average than the cells infected with the original COVID-19 strain.
Hamsters infected with the Delta variant lost more weight and developed more serious lung inflammation compared with the ones infected with the original COVID-19 strain.
To pinpoint the mutation, the team prepared viruses with characteristics of the original COVID-19 strain, as well as viruses created by adding the P681R mutation.
The team found that when cells became infected with viruses containing the P681R mutation, they formed big chunks just like in the experiments with the Delta variant.
The hamsters infected with the mutated viruses also lost more weight and developed more serious lung conditions, similar to the test subjects infected with the Delta strain.
Lung tissues are made up of cells that are arranged in an orderly manner.
The researchers believe that cells that are infected with the Delta variant and become chunks disrupt this order and cause greater damage to the lungs when the cells die.
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