An experiment based on the 2009 H1N1 swine flu pandemic may have helped scientists move closer to developing a universal flu vaccine, according to a new study.
Researchers at Imperial College London, in England, asked 342 staff members and students to donate blood samples right as the pandemic was beginning in autumn 2009. They were also asked to report any symptoms they experienced over the next two flu seasons.
The goal was to determine why some people seem to resist severe illness when exposed to flu bugs. The researchers discovered that people who caught the flu but had only mild or no symptoms had more CD8 T-cells -- a type of virus-killing immune cell -- in their blood at the start of the pandemic.
The authors of the study, published online Sept. 22 in the journal Nature Medicine, believe that a vaccine that stimulates the body to produce more CD8 T-cells could be an effective way to fight flu viruses, including new strains that cross over into people from birds and pigs.
"New strains of flu are continuously emerging, some of which are deadly, and so the Holy Grail is to create a universal vaccine that would be effective against all strains of flu," study leader Professor Ajit Lalvani said in an Imperial College London news release.
"The immune system produces these CD8 T-cells in response to usual seasonal flu. Unlike antibodies, they target the core of the virus, which doesn't change, even in new pandemic strains. The 2009 pandemic provided a unique natural experiment to test whether T-cells could recognize, and protect us against, new strains that we haven't encountered before and to which we lack antibodies," Lalvani explained.
"Our findings suggest that by making the body produce more of this specific type of CD8 T-cell, you can protect people against symptomatic illness. This provides the blueprint for developing a universal flu vaccine."
Lalvani added: "We already know how to stimulate the immune system to make CD8 T-cells by vaccination. Now that we know these T-cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others. This could curb seasonal flu annually and protect people against future pandemics."