American researchers have developed a deadly new strain of Covid in a lab – an echo of experiments many fear started the pandemic.
The mutated variant – a hybrid of Omicron and the original Wuhan virus – killed 80 percent of the mice infected with it at Boston University.
However, when a similar group of rodents were exposed to the standard Omicron strain, they all survived and showed only “mild” symptoms.
The scientists also infected human cells with the hybrid variant and found that it was five times more infectious than Omicron.
This suggests the man-made virus could be the most contagious form yet.
In the new research, a team of scientists from Boston and Florida extracted Omicron’s spike protein — the unique structure that binds to and enters human cells.
They linked Omicron’s spike to the original wild-type strain that first emerged in Wuhan at the start of the pandemic.
In the paper, they wrote, “While Omicron causes a mild, nonfatal infection in …mice, the Omicron S-carrying virus causes severe disease with a mortality rate of 80 percent.”
The researchers said it signals that while the spike protein is responsible for infectivity, changes to other parts of its structure determine its lethality.
The scientists also studied the effect of the different strains on human lung cells grown in the laboratory.
Covid attaches itself to human cells with its spike protein, instructing healthy cells to make copies of themselves.
Scientists measured how many copies each variant made from the health cells.
They found that the hybrid strain produced five times more virus particles than the original Omicron.
The scientists concede that the hybrid virus is unlikely to be as deadly in real humans as it is in mice.
They noted that one limitation of their study was the specific breed of mice used, as other types of mice are more similar to humans.
Mice and humans also do not have identical immune responses, as there are differences in DNA and genes between species.
For example, the genes that regulate the immune system behave differently, and the response to stress is different in mice and humans.
The types of mice used in the study were specifically designed to study severe Covid infections, but no mouse model currently replicates all aspects of Covid in humans.
The laboratory at Boston University’s National Emerging Infectious Diseases Laboratories is one of 13 biosafety level 4 laboratories in the United States.
These are laboratories authorized to handle the most dangerous pathogens. There are also facilities in Texas, Atlanta and Manhattan, Kansas.
Experiments in these labs often involve tinkering with animal viruses to advance treatments and vaccines that could be used in a future outbreak.
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https://metro.co.uk/2022/10/17/scientists-develop-new-covid-strain-that-would-kill-80-of-people-infected-17581534/ Scientists are developing a new strain of Covid that would kill 80% of those infected