Dal researchers shed new light on pandemic flu virus

A Dalhousie Medical School study has shed new light on how the influenza A virus – the virus responsible for flu pandemics – infects the body and makes people sick. Findings were recently published in the Journal of the Federation of American Societies for Experimental Biology (FASEB).

Key Points:

Through previous infection or vaccination, our immune systems recognize influenza viruses and limit their ability to cause infection. Because influenza changes every year, our immune systems are constantly being challenged to recognize new strains. For this reason, flu vaccines need to be reformulated annually.
Our bodies also have a first line of defence known as innate immunity; it does not depend on training from previous infection or vaccination. Innate immune defences allow our cells to recognize when they are infected with influenza viruses and activate antiviral programs that try to stop the viruses from multiplying and spreading to nearby cells.
Researchers at Dalhousie Medical School have discovered a new aspect of the body's innate defences against infection. They've shown that this defence involves the creation of structures inside the cell that trap viruses and prevent them from multiplying. These traps are called stress granules. The research team found that influenza is very good at preventing these stress granule traps from forming, meaning flu infection can take hold more easily than some other infections.
The researchers also found that a specific influenza virus protein called NS1 is what's responsible for preventing stress granules from forming and protecting the cell. When NS1 was disabled, the researchers observed that the influenza virus could no longer stop stress granules from forming; the cell was able to trap the virus and keep the infection from progressing.
This research was funded by the Canadian Institutes of Health Research and the Nova Scotia Health Research Foundation.

Pull Quotes:

"Our study is the first to examine the relationship between influenza virus infection and stress granules, and clearly shows that the virus has evolved multiple different ways to counter our stress granule-based defences." -- Dr. Denys Khaperskyy, post-doctoral fellow, Department of Microbiology & Immunology (Dr. Khaperskyy performed all of the hands-on experimentation and made the initial discovery of influenza virus subversion of stress granule defences)
"Our work suggests that stress granules may be harnessed to control influenza virus infection. We're now searching for ways to bypass the effects of the NS1 protein and prompt the cells to unleash the stress granule defences to limit influenza virus replication." -- Dr. Craig McCormick, principal investigator and assistant professor, Department of Microbiology
"Our work clearly demonstrates the complexity of influenza virus infection and highlights the need to continue basic efforts to understand what makes it such a successful virus in terms of infecting our bodies." -- Dr. Todd Hatchette, associate professor, Department of Microbiology & Immunology, and director of Virology and Immunology at the QEII Health Sciences Centre
By better understanding how influenza interacts with our cells, we can start to look at how we can use this information to generate new treatment or prevention strategies." -- Dr. Todd Hatchette, associate professor, Department of Microbiology & Immunology, and director of Virology and Immunology at the QEII Health Sciences Centre