Researchers from the University of Alberta are currently testing an antiviral drug that is proven to cure a cat coronavirus that they hope may also work as a protease inhibitor against COVID-19.
The team will be testing protease inhibitors that were originally developed in 2003, just after the deadly outbreak of severe acute respiratory syndrome (SARS). Two U of A scientists who studied stopping the virus from replicating are chemist John Vederas and biochemist Michael James.
Now Vederas will be joined by biochemist Joanne Lemieux and virologist Lorne Tyrrell to test the protease inhibitors against the deadly coronavirus COVID-19 infection.
Lemieux recently talked about the excitement surrounding the project:
Our lab has been working as fast as we can to get our results out. We have not taken weekends, the days of the week have blurred. We’re all working non-stop to get results as fast as we can. It’s nice to think that we can make a difference.
Protease Inhibitors
Protease inhibitors are antiviral drugs that are used to treat a variety of diseases including HIV/AIDS, and hepatitis C. Around 5 to 10 percent of all drugs developed worldwide are classified as protease inhibitors.
They are quite useful because proteases are enzymes that enable a virus to replicate inside of a host, such as humans or animals. Many people are aware by now that COVID-19 is a ribonucleic acid or RNA virus.
Lemieux explains how a protease inhibitor works against the RNA viruses:
When the virus enters a cell, the RNA is translated into a polypeptide—a long single protein chain—and the protease chops that long-chain into many different parts, which then cause the damage. If the protease does not work, the virus cannot replicate in the cell, so it’s a pretty clear antiviral target.
John Vederas’ lab is part of the Faculty of Science at the University where they will produce the inhibitor drug. Lemieux’s lab will determine the crystal structure in the COVID-19 protease and observe how well it works after it gets blocked. Finally, Tyrrell will test the effectiveness of the viral load in cell cultures. Tyrrell’s lab already has one hurdle cleared as they are approved by the Federal government to work with deadly pathogens.
What does this have to do with a Cat?
The genome sequencing of the protease in the coronavirus and the protease from the original SARS virus are 96 percent identical. “Of the 306 amino acid residues in the chain that makes the 3CL protease of the ‘Wuhan’ virus, only 12 are different and they are highly similar in properties,” stated the researchers.
This same protease inhibitor was recently demonstrated by American veterinary investigators to cure cats of a coronavirus condition known as feline infectious peritonitis, which has a high fatality rate.
Lemieux and the other researchers are excited about the possibilities while cautioning it still needs to be tested and proven in humans:
It is very exciting that the drug was effective and tolerated in cats. The key compound affected cures or [shows] significant remissions in all the cats.
The study is expected to take around two months before they know whether the protease inhibitor will work against the COVID-19 virus. If successful human trials would need to follow. According to Tyrrell pharmaceutical companies are often reluctant to develop drugs. With a worldwide pandemic, hopefully, this would be different.
“With the crisis right now, it is critical that virologists translate some of the things we are discovering into products,” said Tyrrell.
