Antibodies from 1918 Flu Survivors Protect Against the Virus

Sera from all the survivors demonstrated positive immune responses to the 1918 virus, suggesting that they still possessed antibodies to the virus.

A subset of seven donor samples tested had circulating B cells that secreted antibodies that bound the 1918 haemagglutinin (HA) protein antigen. The investigators isolated B cells from these subjects and generated five monoclonal antibodies that showed potent neutralizing activity against the 1918 virus from three separate donors. These antibodies also cross-reacted with the genetically similar HA of a 1930 swine H1N1 influenza strain, but did not cross-react with HAs of more contemporary human influenza viruses. The antibodies bound to the 1918 HA protein with high affinity, had exceptional virus-neutralizing potency, and protected mice from lethal infection.

"The B cells have been waiting for at least 60 years – if not 90 years – for that flu to come around again,” said senior author Dr. James Crowe, professor of pediatrics at Vanderbilt University. "That is amazing…because it is the longest memory anyone's ever demonstrated. The lessons we are learning about the 1918 flu tell us a lot about what may happen during a future pandemic.”

The investigators concluded their paper in the August 17, 2008, online edition of the journal Nature with the observation: "These studies demonstrate that survivors of the 1918 influenza pandemic possess highly functional, virus-neutralizing antibodies to this uniquely virulent virus, and that humans can sustain circulating B memory cells to viruses for many decades after exposure—well into the tenth decade of life.”

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