The cat’s out of the bag: How a drug for feline coronavirus could be used to treat COVID-19 in humans

Dr. Joanne Lemieux

Several years ago, Dr. Joanne Lemieux worked in a lab focused on the coronavirus that caused the SARS crisis in 2003. Although she was not studying the virus herself at the time, she became acquainted with the work of her colleagues as they focused on a particular protein that the SARS virus uses to make copies of itself.

Specifically, her colleagues were testing “inhibitors” to prevent the virus from being able to use the protein it needed. This is an important type of investigation because if the virus can’t use that key protein, then it can’t replicate—and if it can’t replicate, it can’t infect more cells. Finding ways to stop replication is at the root of antiviral drug development, as halting the replication will halt the infection.

Dr. Lemieux, a structural biologist who now has her own lab at the University of Alberta, studies proteases—the enzymes that our cells use to break down proteins for a variety of uses. Proteases can be highly specific, snipping a given protein in a precise place so that the resulting pieces can be used to build something else (almost like cutting measured bits of fabric to make a quilt). This has health implications because if a needed protease isn’t functioning properly, the results can lead to disease. This makes proteases an interesting target for drug development, as fixing a faulty enzyme could be beneficial—or, when it comes to viral infection, blocking access to a needed enzyme could stop the virus from replicating altogether.

Science is best when it is a team sport, and it is the combination of her past experience and current specialty that led Dr. Lemieux to explore this type of antiviral drug development.

Back when Dr. Lemieux’s colleagues were testing those inhibitors against the virus, SARS was not a global threat to human health and SARS-CoV-2, the virus that causes COVID-19 disease, had not yet appeared. There was, however, a different coronavirus in their crosshairs: feline infectious peritonitis (FIP), a strain of feline enteric coronavirus (FECV) that causes fatal infection in cats. With slight modifications to the chemical compounds they used on the SARS virus, the team was able to develop a drug that worked as they intended: it stopped the FIP virus from replicating and cured almost all of the cats in the study.

Dr. Lemieux is now leading the team that includes chemists and a virologist from the University of Alberta to see if the drug used for that feline infection could be used to treat humans diagnosed with COVID-19. They are currently testing the drug in cells infected with SARS-CoV-2 to assess its ability to stop the virus from replicating. It is an intensive process that involves looking at the three-dimensional structures of the chemical compounds in the drug and how they (quite literally) sit in the virus’s way, blocking its ability to break down and use a protein that it would normally need to build copies of itself. As of late April 2020, the preliminary data looks promising—and since the drug is already known to be safe in animals, Dr. Lemieux hopes that the next step will be to test it with human clinical trials.

Dr. Lemieux is heartened by the public’s interest in the science behind potential treatments for COVID-19, and she wants to assure them that they have put their trust in the right place. “Viruses have been studied for decades,” she explains, emphasizing how crucial it is to support and maintain rigorous research at all times, not only during a pandemic. “Even though SARS-CoV-2 is a new form, scientists know what needs to be done—what we need to study right now—and we’re on it.”

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