SARANAC LAKE - New research from the Trudeau Institute may help to explain why the nasal-spray vaccine FluMist has been effective in protecting people against influenza.
The research is published in this month's issue of Vaccine. The journal article is entitled "Live attenuated influenza vaccine (LAIV) impacts innate and adaptive immune responses" and was authored by Trudeau Institute scientist Laura Haynes and her colleagues.
Haynes said the research examined how LAIV, commonly known as FluMist, elicits protection.
"Influenza infection normally induces a massive inflammatory response in the lungs that leads to significant illness and increases the susceptibility to secondary bacterial infections," Haynes said in a news release from Trudeau. "The most efficient way to prevent influenza infection is through vaccination. To date, the mechanism of how FluMist induces protection has been unclear. Our study demonstrates that this vaccine works by inducing a very early non-specific immune response in the lungs in a mouse model of influenza infection."
The very early, non-specific immune response sets the stage for the early influx of virus-specific immune cells, which are necessary for viral clearance. Importantly, this immune response is protective against both matching and non-matching influenza strains; therefore it could provide a level of protection in the case of a newly emergent influenza strain.
In addition, this very early immune response also serves to limit lung inflammation by significantly reducing the levels of inflammatory cytokines and chemokines produced following influenza infection. This finding provides insight into how this influenza vaccine functions and is important because inflammation is a major cause of damage in the lungs, setting the stage for secondary bacterial infections that are common following influenza infection.
The study shows that FluMist vaccine also induces a robust immune response in healthy adult volunteers.
The experiments were carried out in collaboration with the Respiratory Diseases Research Department at the Naval Health Research Center in San Diego, Calif., and were the result of a joint Trudeau-Department of Defense contract.