WASHINGTON, Feb. 15, -- In a scientific tour de force, researchers have decoded the DNA for a key gene in the virus that sparked the deadly Spanish flu pandemic that swept the world in 1918 and may have killed as many as 40 million people. But, the scientists say the genetic blueprint does not explain why the virus was so deadly and was able to stop healthy young soldiers in their tracks, killing them in a day. The newly deciphered gene, called hemagglutinin (HA), is the first of the eight genes in the influenza virus that scientists are investigating, says molecular biologist Ann Reid of the Armed Forces Institute of Pathology in Washington, D.C. She says the scientists worked with tissue samples preserved from soldiers who died in September, 1918, at Ft. Jackson, S.C. and Camp Upton, N.Y. military bases. The third sample came from the frozen body of a woman who died in Alaska in November of the same year and was buried in permafrost, says Reid, a co-author of the study. She adds the researchers are coming close to having the code for three other genes from the notorious germ, and expect to report on their findings later this year. But asked whether this finding will explain why that particular virus sparked the worst worldwide infectious disease epidemic on record, Reid says, 'We don't think it does.' Even when all of the codes are on paper, she says, scientists may know little more than the desperate doctors in 1918 about why the Spanish flu was so virulent.
One problem is that little is known about how variations in genetic structure make some flus a nuisance and others a menace. Dr. Jeffery K. Taubenberger, senior author of the study, says, 'The reason for its lethality may be found in another gene, or in the way its genes worked together.' But Reid says, 'We may get the whole sequence in front of us and not know why it was so virulent.' The scientists focused on the HA gene because it plays a key role in binding to human cells and because it is a major target for the immune system. In some forms of influenza that affect birds, extra DNA at one part of the gene has been shown to lead to serious infections, causing a kind of superinfluenza in which the germ invades tissues all over the body --- lungs, liver, brain and muscle. It's just a horrendous and very rapidly fatal infection, says Reid. Scientists thought that a similar genetic structure might have been the key to the deadliness of the 1918 flu, even though such a mutation had never been seen in the human virus or in bird flus of the same family. But, Reid says, 'It was an interesting idea and it certainly would have been avery attractive thing to follow up on had we found it, but we didn't.' The scientists say nothing else in the genetic makeup of the HA gene from the 1918 virus can explain why it killed so many people, including those between ages 25 and 35, a group that rarely dies from the flu. Reid says, 'That is so unlike any other influenza virus.' The study is published in Tuesday's issue of the Proceedings of the National Academy of Sciences. In an editorial on the study, Robert G. Webster of the department of virology and molecular biology, St. Jude Children's Research Hospital, Memphis, calls the work a tour de force. He points out, however, that many of the biological properties of the 1918 pandemic virus remain to be revealed. Webster says that the full DNA sequence of the 1918 flu may help scientists design vaccines and drugs to fight a new killer virus if one ever emerges. ---
Copyright 1999 by United Press International. All rights reserved. ---