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Researchers inch closer to universal flu vaccine

By Eryn Brown, Los Angeles Times
Published: September 14, 2015, 6:00am

Someday, patients may no longer have to get a new flu shot each year, tailored to the particular strains expected to dominate in a given season. That’s because scientists are homing in on new methods of formulating vaccines that will be able to confer immunity against multiple varieties of influenza — a feat they haven’t been able to achieve in the past.

Last week, two teams reported independently that they had mimicked a tiny portion of the flu virus known as a hemagglutinin stem, helping them develop experimental vaccines that protected animals against several flu types.

“This is an early step,” said Barney Graham, deputy director of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases in Bethesda, Md., and senior author of one of the research papers outlining the advances. “But it is promising.”

A great deal of the human immune response to influenza is directed against a protein on the virus called hemagglutinin — and in particular, a portion of the protein called the hemagglutinin head, where many mutations occur.

In the 1990s and 2000s, Graham said, scientists learned that some people seemed to develop broadly acting antibodies that neutralized a variety of flus by targeting a different location on the hemagglutinin protein known as the stem, where mutations do not occur as often. But the human immune system doesn’t create antibodies against the stem as readily as it creates them to combat the antigens on the head, in part, researchers think, because of simple geography: The hemagglutinin sits atop the virus with the head exposed and the stem hidden.

The two research groups took different technical approaches to nearly identical concepts, said Andrew Ward, a structural biologist at the Scripps Research Institute in La Jolla, Calif., who was involved in the other research effort.

Hoping to amp up the immune system’s production of stem-specific antibodies that might battle a wider variety of flu viruses, the teams both decided to take the distracting hemagglutinen head out of the picture and create stem-only antigens to incorporate into vaccines.

Once they had built stable molecules, they created vaccines and tested them.

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