Scientists have discovered that the virus behind Covid-19 causes infected cells to develop protruding, fibrous branches, a very unusual structure that allows the virus to attack multiple cells at once.
Researchers led by the University of California, San Francisco have published the first close-up images of the spaghetti-like tentacles taken with an ultra-powerful electron microscope.
“There are long chains that make holes in other cells and the virus passes through the tube from one cell to another,” said Professor Nevan Krogan, director of the UCSF Institute for Quantitative Biosciences who led the project. “Our hypothesis is that this speeds up infection,” Professor Krogan said of the “nasty and sinister” branches.
Images taken by scientists from the laboratory of the National Institutes of Health (NIH) in the US and the University of Freiburg in Germany will be published in the medical journal Cell on Saturday.
Most viruses do not cause infected cells to develop these tentacles. Even those that do, like smallpox, don’t have as many or the same type of branching as Sars-Cov-2, the virus behind Covid-19.
The discovery has highlighted a number of drugs that could be deployed against the disease, most of which were previously developed to treat cancer. Professor Krogan said that cancers, HIV or Sars-Cov-2 were looking for the “Achilles heel of the cell.”
“It makes perfect sense for there to be an overlap in anticancer drugs and an antiviral effect,” he said.
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Initial experiments were performed on African green monkey kidney cells, which have previously been shown to be easily infected with the virus. But the potential drugs were tested in human lung cells.
Potential Covid-19 drugs include silmitasertib, manufactured by Taiwan-based Senhwa Biosciences, which directly inhibits the CK2 enzyme used to build the tubes. Senhwa is already working with the NIH to conduct tests in the U.S.
The researchers compared these cancer treatments to remdesivir, a drug from Gilead Sciences that has been shown to reduce recovery times in a large trial. They found five drugs that were more powerful against the virus, including Xospata, also known as gilteritinib, manufactured by Astellas Pharma of Japan and already approved by the US Food and Drug Administration for patients with leukemia.
Other possible treatments include abemaciclib, an FDA-approved drug sold as Verzenium by Eli Lilly, and ralimetinib, also developed by Lilly, based in Indianapolis, as well as dasatinib, an approved drug from Bristol-Myers Squibb.
The Coronavirus Research Group at the Institute for Quantitative Biosciences, which includes researchers from New York to Paris, specializes in finding drugs that target the human proteins the virus needs to reproduce, rather than directly targeting the virus.
In an earlier article published in the journal Nature, they discovered potential medications that could be reused, including over-the-counter cough and allergy medications.
So far, their work has focused on the laboratory, but they are looking to start human clinical trials. Scientists also suggest trying these new drugs in combination with remdesivir.
