New discovery may make universal flu vaccine possible

VANCOUVER - Canadian researchers have found a potential way to develop universal flu vaccines and eliminate the need for seasonal flu vaccinations, making influenza pandemics a thing of the past.

The research, published Tuesday in the journal Frontiers in Immunology, finds that the 2009 H1N1 "swine flu" vaccine triggers antibodies that protect against many influenza viruses, including the lethal avian H5N1 "bird flu" strain.

According to John Schrader, the lead author of the study, the flu virus has a protein called hemagglutinin, or HA for short, which is like a flower with a head and a stem. The flu virus binds to human cells via the head of the HA, which is also the target of current flu vaccines to prevent infections.

"But because the flu virus mutates very quickly, this part of the HA changes rapidly, hence the need for different vaccines every flu season," said Schrader, who is also director of University of British Columbia's Biomedical Research Centre.

However, the researchers find that the 2009 pandemic H1N1 vaccine induced broadly protective antibodies capable of fighting different variants of the flu virus.

"This is because, rather than attacking the variable head of the HA, the antibodies attacked the stem of the HA, neutralizing the flu virus," says Schrader. "The stem plays such an integral role in penetrating the cell that it cannot change between different variants of the flu virus."

The characteristics of the human immune system make it difficult for influenza vaccines to induce broadly protective antibodies against the HA stem, but the pandemic H1N1 swine flu is different as humans have not been exposed to a similar virus, says Schrader.

Schrader has evidence that a vaccine based on a mixture of influenza viruses not circulating in humans but in animals should have the same effect and potentially make influenza pandemics and seasonal influenza a thing of the past.

Seasonal influenza causes serious illnesses in three to five million people and 200,000 to 500,000 deaths each year. The 2009 H1N1 pandemic killed more than 14,000 people worldwide.