Universal flu vaccine closer to reality

A universal flu vaccine that can protect against many strains of the virus may be closer to reality, after scientists found that it is possible to create more effective vaccines against the ever-mutating virus.
"While the conventional flu vaccine protects only against specific strains, usually three of them, our experiments show that by including modified antibodies within the vaccine it may be possible to elicit broad protection against many strains simultaneously," said senior study author Jeffrey Ravetch from the Rockefeller University in US.
"We believe these results may represent a preliminary step towards a universal flu vaccine, one that is effective against a broad range of the flu viruses," Ravetch said.

The team describes a new strategy that revolves around antibodies, immune proteins that target specific foreign proteins, called antigens.
One end of the antibody latches on to an antigen, the other end, called the Fc region, binds to immune cells and so helps coordinate the immune response.
It was already known that chemical modifications to antibodies' Fc region altered their interactions with immune cells, including B cells, which produce antibodies.

In experiments that began with human volunteers, the team, led by Taia Wang and Jad Maamary, both in Ravetch's lab, investigated how changes to this region might be used to bolster an immune response: namely the production of more potent antibodies against the flu virus.

The influenza virus makes for a difficult target for vaccines because its strains are so diverse, and new ones are constantly emerging.
Types A and B cause seasonal flu epidemics. Influenza A viruses are further broken down into subtypes based in part on their surface proteins, which include hemagglutinin, the 'H' in H1N1, for example. The subtypes are further divided into strains.
A number of strategies have been proposed to create a universal flu vaccine. Ravetch's lab suggested a new alternative - chemical modifications to the Fc region of antibodies.
First, the researchers vaccinated healthy volunteers with a seasonal flu vaccine containing an inactivated strain of the H1N1 virus.

They then tracked the volunteers' immune responses via blood samples, keeping an eye out for chemical modifications to antibodies against the hemagglutinin protein.
About seven days after the vaccination, they saw a spike in sialylated antibodies, meaning sialic acid, an important signalling molecule, had been added at a specific spot on the Fc region.
The greater the sialylation, the better a person's response to the vaccine.
The study was published in the journal Cell.