Sabin collected four samples of the virus in 1960 for Andre Loffthe virologist of the Pasteur Institute and the winner of the Nobel Prize in 1965 had sent. These viruses had been adapted in the laboratory to grow at temperatures below human body temperature, and Sabin thought they might be a good basis for vaccine development. At that time, Loff was researching the effect of fever on pathogens. According to the Pasteur Institute, these samples are recognized as “major legacies for science and public health”.
now inclined toThe polio virus researcher at the Pasteur Institute and his colleagues have found that one of the strains of the virus named “Glen” is genetically similar to the virus named “Saukett A”. Socta is a group of polioviruses that was isolated in the United States in the 1950s and is still used in the production of inactivated polio vaccines. But Glenn is strikingly similar to the virus that was taken from a four-year-old boy in central China in 2014.
The virus may have leaked elsewhere in the world before it was detected in China
Researchers at the Wuhan Institute had previously determined the sequence of the Chinese child virus and named it “WIV14”. They reported in 2017 that the virus was similar to the Sabin 3 strain used to make oral polio vaccines. Live virus in oral vaccines can remain in circulation and mutate. The Wuhan team concluded that the Sabin 3 virus used for immunization eventually evolved into WIV14.
In order to better understand the issue, Pasteur researchers also sequenced the Soketa virus, whose genome was relatively unknown. They found that WIV14 differs from SocketA by only 70 nucleotides, while it differs from Sabin3 by more than 800 nucleotides; This means that WIV14 is not derived from Sabin 3, but from a strain much closer to SocketA or even from SocketA itself.
The authors of the article wrote that the child’s virus sample may have somehow been infected with Soketa in the laboratory or elsewhere. But if the child was indeed infected with WIV14, the virus could only remain so similar to Socket A if it had been in an inactive state for decades, either in a natural reservoir such as permafrost or, given the strain used in vaccine production. , remaining in the freezers of vaccine production centers. Then, the virus is somehow released. Such an event did not necessarily happen in China; The virus may have leaked elsewhere in the world before it was detected in China.
“Currently, the authors do not favor any scenario over the other because there is no scientific argument to support one scenario over the other,” said the Pasteur Institute’s media consultant in an interview with Science magazine.
Famular also agrees with the Pasteur Institute researchers, but other researchers are more inclined to the virus leakage hypothesis. Adam Loringan evolutionary virologist from the University of Michigan and editor of the paper, says that errors in the lab are always a possibility. But it seems that a leak from the vaccine production center is more likely. “I’m totally convinced,” he says.
The result of the virus leak investigation will probably never be revealed
Roland Sutter who until 2020 headed the research of the Global Polio Eradication Initiative project, believes that the hypothesis of leakage from the laboratory is more likely, but adds that the leakage does not necessarily happen from vaccine manufacturing facilities. Socket polio strains are used to make inactivated polio vaccines in Europe, but manufacturers in China, Japan and Korea use attenuated strains of Sabin in their inactivated vaccines, he says.
Universities that teach virology can be another source of virus spills, Sutter says. “The socket strain of polio is much easier to control, which is probably why it’s still used in many places to teach virology,” he argues. Sutter adds that it is very important to identify the sources of virus leaks and any disclosures in this regard. He says he wouldn’t be surprised if their paper has already sparked research in China. Of course, the results of such investigations may never be disclosed.
