Common vaccine for all flu

Universal Flu Vaccines Charge Ahead

Researchers and biotech companies are bringing a universal flu vaccine closer to reality.

http://www.the-scientist.com/?articles.view/articleNo/33933/title/Universal-Flu-Vaccines-Charge-Ahead/

It’s a frustrating fact of life that coming down with influenza one year doesn’t guarantee anyone a flu-free season the next year. Even the flu vaccine doesn’t provide full-proof protection, as it covers only a select few strains of the virus—a selection that’s based on the World Health Organization’s best bet as to which strains around the world will be most prevalent in the coming flu season.

Unfortunately, those predictions are proved wrong about one time out of 20, explained Sarah Gilbert, who leads the Human Influenza Vaccine Programme at the University of Oxford’s Jenner Institute.

However, some researchers are getting closer to creating the ever-elusive universal flu vaccine, which could protect against a number of influenza viruses at once, including pandemic strains. If successful, universal flu vaccines would take the guesswork out of vaccine planning, and only require booster shots every few years.

One antibody to bind them all

Influenza is an RNA virus that uses its hemagglutinin (HA) protein like a key to allow it to enter and infect target host cells. In response to infection, or to a typical flu vaccine, the body produces antibodies that bind the head of the HA molecule, preventing free-floating virus from entering and infecting cells. However, the head is also the part of the HA protein that the virus most frequently changes via mutation, making the antibodies produced against one strain ineffective against another.

The answer to creating a vaccine that protects against many strains lies in forcing the immune system to make antibodies against the portions of the HA molecule that are shared, or genetically conserved, among most influenza viruses, thus creating a more universal vaccine. But, for unknown reasons, most vaccines don’t elicit such antibodies. So researchers are now trying new ways of enticing the immune system into making antibodies that recognize these general targets and neutralize many types of influenza at once.

“Up until about 4 years ago, we didn’t know much about human broadly neutralizing antibodies,” said Ian Wilson, a structural biologist at The Scripps Research Institute. But the last few years, researchers have found individuals who produce  antibodies that neutralize a wide variety of both influenza A and B strains, showing that “a universal vaccine is possible if you can elicit the same types of antibodies” in others, said Wilson.