Virus-killing immune cell may be key to universal flu vaccine
The scientists compiled blood samples taken during the 2009 swine flu pandemic and found that individuals who avoided severe illness had more CD8 T cells in their blood at the beginning of the pandemic. The team said that a vaccine stimulating the body to produce more CD8 T cells could be effective at preventing flu viruses from causing serious disease.
"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," Ajit Lalvani, the leader of the study, said.
Lalvani's team found that individuals with fewer CD8 T cells in their blood fell more severely ill during the swine flu pandemic in fall 2009. Patients who caught flu but had no symptoms or only mild symptoms had more of the cells. While experimental models previously suggested that T cells could protect against flu symptoms, the idea was never tested in humans during a pandemic until now.
"The immune system produces these CD8 T cells in response to usual seasonal flu," Lalvani said. "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 said scientists already know how to stimulate the immune system to make CD8 T cells through vaccination. The findings of the study may prompt the development of CD8 T cell vaccines to prevent individuals from getting flu symptoms and transmitting infection to others.