Karen Maxwell (Photo by Erin Howe)
1 April 2026
By Erin Howe
This story was originally published on the Temerty Faculty of Medicine News website.
University of Toronto Professor and member of the Emerging & Pandemic Infections Consortium Karen Maxwell has been honoured with a 2026 Peter Gilgan Canada Gairdner Momentum Award, for uncovering the molecular strategies bacteria use to defend against viruses and revealing how viruses that infect and destroy bacteria — called bacteriophages — evade these defences.
The research by Maxwell, a professor in the department of biochemistry at U of T’s Temerty Faculty of Medcine who holds the Canada Research Chair in Bacteriophage Biology and Therapeutics, helps pave the way for next-generation precision phage therapies to combat antibiotic-resistant infections.
Maxwell is one of two researchers to receive this year’s award, which recognizes mid-career investigators for exceptional scientific research contributions with continued potential for impact on human health.
“I did my PhD in molecular genetics and a master’s degree before that at U of T, and have been attending Gairdner week since my student days,” Maxwell said. “It’s always exciting to see the science and the researchers these awards recognize, and to be part of that group is amazing.”
“I share this honour with my trainees and lab staff, because I absolutely wouldn’t be here without their hard work,” Maxwell added.
The Canada Gairdner Awards were established in 1957 and are Canada’s most prestigious prizes for health-sciences research. Since then, 434 awards have been bestowed on laureates from over 40 countries, to celebrate pioneering biomedical and global health research that has transformed the understanding of human health and disease.
The awards are also seen as a precursor to the Nobel Prize. Nearly a quarter of Gairdner recipients have subsequently received Nobel Prizes.
Maxwell’s research integrates genetics, biochemistry and structural biology to uncover sophisticated molecular strategies.
Her lab discovered and characterized multiple new bacterial immune systems and the mechanisms they regulate when these systems are activated during infection.
The group demonstrated how bacterial immunity works and how these defences are deployed when needed. Among Maxwell’s key discoveries is that some bacteria produce small chemical compounds that block viral replication as a form of “chemical immunity.”
Maxwell’s work also shows that bacterial immunity is shaped by genes carried on mobile pieces of DNA, including viral DNA left behind in bacterial genomes. These dormant viral elements can actively protect their hosts by detecting invading viruses and triggering rapid immune responses.
Antibiotic-resistant bacterial infections threaten millions of lives around the world each year.
Maxwell’s research has transformed how scientists understand ‘the evolutionary arms race’ between bacteria and the viruses that infect them, and how bacteria defend themselves from phages and develop counter-defences to overcome bacterial immunity.
Her discoveries have provided a foundation for the design of precise, next-generation phage-based therapies.
“Maxwell is a leading figure in redefining our understanding of phages and phage–bacteria interactions,” said Sylvain Moineau, a professor of microbiology at Université Laval, who is also curator of the Félix d’Hérelle Reference Center for Bacterial Viruses. He previously held the Canada Research Chair in Bacteriophages and has followed Maxwell’s pioneering work over the years.
“Her findings significantly expand the landscape of microbial immunity and spark new lines of exploration in biotechnology, medicine, and phage-based therapy,” Moineau said.
There are several implications for Maxwell’s work, including the potential to discover new tools similar to CRISPR-Cas9, a fast and precise gene-editing technology that scientists adapted from a natural bacterial defense mechanism. Her team also played a role in the discovery of the first inhibitors of CRISPR-Cas9 systems, which scientists are now using to develop more precise gene-editing tools for a wide range of applications in biotechnology and health care.
Researchers are also exploring phages as a potential alternative to antibiotics to treat antibiotic-resistant infections.
As well, phages have the potential to reveal fundamental information about the connection between bacterial immunity against viruses.
“Learning how the how bacterial immunity works can reveal really important information about how human immunity works as well,” said Maxwell.
In industrial applications, Maxwell’s discoveries could be harnessed to control phage infection in applications like cheese and yogurt making. In the manufacturing process for fermented foods, starter cultures contain bacteria; a phage infection can spoil an entire batch, with costly consequences for food producers.
Maxwell’s Canada Gairdner Award is just her most recent recognition. In 2020, she received the Natural Sciences and Engineering Research Council’s John C. Polanyi Award and last year, she was honoured with a Temerty Medicine Research Excellence Award.
Read more about each of this year’s Canada Gairdner Award Laureates.