Method for fast human antibodies against flu could find broad use

With a detailed look at the antibodies stimulated by booster vaccination, the scientists also were able to address an issue that confounds health authorities trying to predict which viral strains will prevail in the upcoming flu season.

Doctors have worried about a phenomenon called "original antigenic sin," where immunizing someone against a certain strain can handicap them in responding to a related strain.

"We found that these early B cell responses are able to focus on the new virus, even though the immune system has seen related viruses before," says Wrammert, who is the paper's first author. B cells are the white blood cells that make antibodies.

The authors conclude that original antigenic sin is uncommon for healthy adults receiving influenza vaccination.

The methods previously used to make human monoclonal antibodies can be relatively laborious, Ahmed says. They involve sifting through human B cells and looking for those that make the right antibodies, or vaccinating mice and "humanizing" the mouse antibody genes by altering them so that they resemble human antibodies.

To make human antibodies against influenza, the Emory and University of Oklahoma researchers isolated antibody-secreting cells (plasma cells) from volunteers' blood a week after vaccination and cloned the antibody genes from these antibody-secreting cells.

"There's a transient window where the cells that are making high-quality antibody are found in the blood," Ahmed says. ÒThey disappear from the blood afterwards, but at a certain point, most of the antibody-secreting cells are making antibody specific for flu virus."

The research was funded by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.