WASHINGTON, United States — The genetic variation of the novel coronavirus that dominates the world today infects human cells more readily than the original that emerged in China, according to a new study published in the journal Cell on Thursday.
The lab-based research suggests this current mutation is more transmissible between people in the real world compared to the previous iteration, but this hasn’t yet been proven.
“I think the data is showing that there is a single mutation that actually makes the virus be able to replicate better, and maybe have high viral loads,” Anthony Fauci, the United States’ top infectious disease specialist, who wasn’t involved in the research, commented to Journal of the American Medical Association.
“We don’t have a connection to whether an individual does worse with this or not. It just seems that the virus replicates better and may be more transmissible, but this is still at the stage of trying to confirm that,” he added.
Researchers from the Los Alamos National Laboratory in New Mexico and Duke University in North Carolina partnered with the University of Sheffield’s COVID-19 Genomics UK research group to analyze genome samples published on GISAID, an international resource for sharing genome sequences.
They found that the current variant, called “D614G,” makes a small but potent change in the “spike” protein that protrudes from the surface of the virus, which it uses to invade and infect human cells.
The scientists first posted their paper to the medical preprint site bioRxiv in April, where it received 200,000 hits, a record.
But it was initially criticized because the scientists had not proved that the mutation itself was responsible for its domination; it could have benefitted from other factors or from chance.
The team therefore carried out additional experiments, many at the behest of the editors of Cell.
They analyzed the data of 999 British patients hospitalized with COVID-19 and observed that those with the variant had more viral particles in them, but without this changing the severity of their disease.
Laboratory experiments meanwhile showed that the variant is three to six times more capable of infecting human cells. “It seems likely that it’s a fitter virus,” said Erica Ollmann Saphire, who carried out one of the experiments at La Jolla Institute for Immunology.
‘This variant is the pandemic’
But everything at this stage can only be said to be “probable”: In vitro experiments often do not replicate the dynamics of a pandemic.
As far as we know, although the variant circulating right now is more “infectious,” it may or may not be more “transmissible” between people.
Short-term immunity
Meanwhile, test monkeys infected with the novel coronavirus responsible for the COVID-19 pandemic were protected from reinfection for up to 28 days later, a Chinese study out Thursday in the journal Science said.
While the monkeys displayed initial immunity, it’s unclear how long such immunity will last in humans – it will be necessary to wait months, or even years, to know if the millions of people infected at the start of the pandemic are protected from re-infection.
Scientists from Peking Union Medical College performed an experiment on rhesus macaques, often used because of their similarities to humans, to find out if they have a short-term immunity to the virus.
Six rhesus macaques were infected in their trachea with a dose of the SARS-CoV-2 virus. They developed mild to moderate symptoms, and took about two weeks to recover.
Twenty-eight days after the first infection, four of the six monkeys received another dose of virus, but this time, despite a brief rise in temperature, they showed no sign of reinfection, the study authors wrote.