Immune cells of 1918 show long memory

Antibodies from survivors of the 1918 flu pandemic, the worst in human memory, still protect against the highly deadly virus, researchers reported on Sunday.

The findings by a team of influenza and immune system experts suggest better ways to fight viruses - especially new pandemic strains that emerge and spread before a vaccine can be formulated.

The survivors, now aged 91 to 101, all lived through the pandemic as children. Their immune systems still carry a memory of that virus and can produce proteins called antibodies that kill the 1918 flu strain with surprising efficiency, the researchers report in the journal Nature.

"It was very surprising that these subjects would still have cells floating in their blood so long afterward," said Dr James Crowe of Vanderbilt University in Tennessee, who helped lead the study.

The antibodies also protected mice from the 1918 virus, which swept around the world at the end of World War I killing between 50 million and 100 million people, Crowe's team reports in the journal Nature.

Remarkable antibodies

"The antibodies that we isolated are remarkable antibodies. They grab onto the virus very tightly and they virtually never fall off," Crowe said.

"That allows them to kill the 1918 virus with extreme potency, meaning it takes a very small amount of antibody."

The human body has two systems for fighting off bacterial and viral invaders. One system uses so-called T-cells while the other employs B-cells, made in the bone marrow, which in turn make antibodies to both flag and directly attack the targets.

Dr Christopher Basler and colleagues at the Mount Sinai School of Medicine in New York tested the 1918 survivors and found that in most of them, the B-cells made antibodies highly attuned to the 1918 flu strain.

Dr Terrence Tumpey at the US Centres for Disease Control and Prevention had worked on a team that resurrected the 1918 virus taken from buried victims of the epidemic and tested this virus in mice.