Antibodies to 1918 flu pandemic may provide means to tackle bird flu threat

Scientists in the United States have discovered that elderly survivors of the original 1918 flu pandemic, still have immunity to the virus.

Researchers at Monroe Carell Junior Children's Hospital at Vanderbilt, have recovered antibodies to the virus, ninety years after it first appeared and caused the deaths of almost 50 million people worldwide.

They also suspect the antibodies could provide effective treatments should another flu pandemic appear imminent.

In a study, led by Dr. James Crowe Junior, a professor of pediatrics and director of the Vanderbilt Program in Vaccine Sciences, researchers collected blood samples from 32 survivors age 91-101 years and found that all reacted to the 1918 virus, suggesting that they still possessed antibodies to the virus.

Samples of the virus used were collected by researchers from Mount Sinai and the Armed Forces Institute of Pathology in 2005 and were taken from the bodies of people killed in the outbreak whose bodies, and the virus, had been preserved in the permanently frozen soil of Alaska.

Professor Crowe's laboratory was able to make antibodies to the 1918 flu from eight of the samples by isolating the rare B cells which are the immune cells that produce antibodies, and grow them in culture.

Seven produced antibodies to a 1918 virus protein, suggesting that their immune systems were waiting on standby for a long-awaited second outbreak.

The cells showing the highest levels of activity against the virus were then fused with "immortal" cells to create a cell line that secretes monoclonal (or identical) antibodies to the 1918 flu.

These antibodies reacted strongly to the 1918 virus and cross-reacted with proteins from the related 1930 swine flu but not to more modern flu strains.

In order to test if these antibodies still work against 1918 flu in a living animal, Crowe's collaborators at the Centers for Disease Control and Prevention infected mice with the 1918 flu and then administered the antibodies at varying doses.

It was found that while the mice given the lowest dose of 1918 antibody died, all those given the highest doses of 1918 antibodies survived.

Professor Crowe says although aging typically causes immunity to weaken, these are some of the most potent antibodies ever isolated against a virus and the best antibodies he has ever seen.

The findings suggest that B cells responding to a viral infection and the antibody-based immunity that results, may in fact last a lifetime, even nine or more decades after exposure.

The scientists say these antibodies could be used as potential treatments for future outbreaks of flu strains similar to the 1918 virus and the technology used to develop antibodies against other viruses such as HIV.

Professor Crowe says important lessons being learnt about the 1918 flu can help predict what may happen during a future pandemic.

Researchers at the Scripps Research Institute in La Jolla, California also contributed to the study which was supported by grants from the National Institutes of Health.

Other researchers include Dr. Christopher Basler from the Mount Sinai School of Medicine, and Dr. Eric Altschuler from the University of Medicine and Dentistry of New Jersey Medical School; the study is published online in the journal Nature.