By KENTA NOGUCHI/ Staff Writer
November 13, 2020 at 19:15 JST
The new coronavirus seen with the electron microscope (Provided by the U.S. National Institute of Allergy and Infectious Diseases)
The mutating new coronavirus now ravaging Europe and the United States is far more infectious than the original strain that flared in Wuhan and threw the central China city into a months-long "lockdown," a study shows.
Research led by Yoshihiro Kawaoka, a professor of virology at the University of Tokyo’s Institute of Medical Science, and Ralph Baric, a professor of epidemiology at the University of North Carolina in the United States, announced their findings in the U.S. magazine Science on Nov. 13.
The initial outbreak was confined to Wuhan, but quickly began spreading globally.
As it evolved, the D614G-type virus, where the spike protein on the virus surface mutated, spread much wider than the original strain.
This mutated version has been spreading in Japan since March.
Researchers have been unable to figure out how the mutation influences the characteristics of the virus.
The team artificially synthesized the original virus and the mutated type in laboratory conditions to study the degree of infectability on hamsters, which can develop pneumonia, just as when humans are found to have a serious case of COVID-19.
The team members matched a coronavirus-infected hamster with a non-infected rodent and reared them in different cages next to each other. This prevented the hamsters from having physical contact but the distance is close enough for the virus to spread.
The team then placed eight pairs each using the original-type virus and the mutated-type and observed them for about a week.
For the pairs with the mutated-type virus, in five cases the virus emerged in the noses of the non-infected hamsters just two days after the experiment started. The infections occurred two days earlier than those with the original-type.
“We were able to confirm that only one mutation can change the virus characteristics to increase infectability,” Kawaoka said.
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