US scientists take key step towards coronavirus vaccine

There's been a crucial move forward in efforts to develop vaccines and treatments against the new Covid-19 coronavirus, US researchers say.

As of Wednesday, cases of infection with the virus have topped 74 000 (the vast majority in China), including more than 2 000 deaths. Therefore, a quick path to a vaccine and effective antiviral treatment is being sought by scientists worldwide.

Now, researchers from the University of Texas at Austin and the US National Institutes of Health (NIH) say they've created the first 3D atomic scale map of a crucial part of the virus called the spike protein. It's this piece of viral anatomy that attaches to and infects human cells.

Mapping this part of the virus is an essential step in any effort to create vaccines and antiviral drugs that would effectively fight Covid-19, according to the paper published on 19 February in the journal Science.

'We had to jump at it'

The research is being led by Jason McLellan, associate professor of molecular biosciences at UT Austin. Speaking in a university news release, he said his team has spent years studying other coronaviruses, including the SARS-CoV and MERS-CoV that were behind earlier, smaller outbreaks.

McLellan said his group already developed methods to lock coronavirus spike proteins into a shape that makes them easier to analyse and position them as targets for vaccines.

Regarding Covid-19, he said that "as soon as we knew this was a coronavirus, we felt we had to jump at it because we could be one of the first ones to get this structure. We knew exactly what mutations to put into this, because we've already shown these mutations work for other coronaviruses."

Based on these findings, the researchers are working on developing a vaccine. They've produced samples of their stabilised spike protein just two weeks after receiving the Covid-19 genome sequence from Chinese researchers, and it took them about another 12 days to reconstruct the 3D atomic scale map, called a molecular structure, of the spike protein. The journal Science then expedited its editorial process to speed publication of the NIH-funded study.

Under less urgent conditions, all of this typically would have taken many months to complete, McLellan noted.

Antibodies could protect health care workers

The newly mapped structure represents only the extracellular portion of the spike protein, the researchers said. However, that should be enough to trigger an immune response in people and potentially point the way to a vaccine.

McLellan and his colleagues also plan to use their molecule as a "probe" that could be used to isolate antibodies from patients who were infected with Covid-19 and recovered.

Produced in large enough quantities, these antibodies should able to help treat a coronavirus infection soon after exposure, the researchers explained.

For example, the antibodies might be used to protect health care workers and other emergency responders sent into areas with high infection rates on too-short notice for a vaccine to take effect.

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