These University of Washington biologists genetically modified a benign virus by swapping one of its genes for a gene for SARS-CoV-2, the virus responsible for COVID-19. The resulting hybrid virus infects cells and is recognized by antibodies as SARS-CoV-2, but can be handled under ordinary laboratory safety conditions.
“I have never had so many requests for scientific material in such a short time”,
explains lead author Sean Whelan, professor emeritus in the Department of Molecular Microbiology: “We have distributed our hybrid virus to colleagues in Argentina, Brazil, Mexico, Canada and, of course, all over the United States. We have pending inquiries from UK and Germany. Before even publishing our work, we were bombarded with requests ”.
To create this harmless model of SARS-CoV-2, researchers started with the vesicular stomatitis virus (VSV). This virus (which especially infects certain animals) is a “classic” in virology laboratories because it is quite harmless and easy to manipulate genetically. The researchers removed the VSV surface protein gene and replaced it with the SARS-CoV-2 spike protein. The resulting virus targets cells like SARS-CoV-2, but lacks the other genes needed to cause serious disease.
A hybrid virus named “VSV-SARS-CoV-2” : Using serum from COVID-19 survivors and purified antibodies, researchers show that hybrid virus is well recognized by antibodies similar to anti-SARS-CoV-2 antibodies: antibodies and sera that prevent hybrid virus to infect cells also block the SARS-CoV-2 virus; antibodies or sera that fail to do so also fail against SARS-CoV-2.
“Antibodies against the spike protein confirmed to be the most important for protection against infection”,
this suggests that as long as a virus has the spike protein, it is considered by the human immune system to be SARS-CoV-2!
“Huge” implications: this hybrid virus will help scientists evaluate a range of preventive antibody-based treatments against COVID-19. The virus can also be used to assess whether an experimental vaccine triggers neutralizing antibodies, to assess the levels of neutralizing antibodies in people who have been infected, to assess convalescent plasma or to identify antibodies that may give rise to antiviral drugs.
“Plus, since the hybrid virus looks like SARS-CoV-2 to the immune system but doesn’t cause serious disease, it’s a potential vaccine candidate! “ add the researchers who are currently evaluating this potential through preclinical studies.