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Dec. 29, 2008 -- Scientists have identified genes that made the Spanish flu pandemic of 1918 especially deadly. It's a discovery that may prove useful if another flu pandemic breaks out.
Influenza can be fatal, but the 1918 Spanish flu pandemic was in a class of its own. It infected about 500 million people worldwide -- a third of the world's population at the time -- and killed an estimated 20 million to 30 million people, note the University of Wisconsin-Madison's Tokiko Watanabe, DVM, PhD, and colleagues.
Watanabe's team sought genetic reasons about why the 1918 flu was so deadly. They had this clue: Influenza mainly affects the upper respiratory tract, but the 1918 flu also took root in the lungs.
In their lab, the researchers compared the K173 flu virus, which is currently circulating among people, to the 1918 flu virus. And they focused on three genes -- called PA, PB1, and PB2 -- that affected a fourth gene, called NP, to make a key difference.
The researchers took those genes from the 1918 flu virus, subbed them into the K173 flu virus, and tested the resulting virus on ferrets. The tweak let the K173 virus lodge in the ferrets' lungs, mimicking the effects of the 1918 flu virus.
The genetic detective "could identify useful targets for drug intervention when new pandemic viruses begin to emerge," Watanabe and colleagues write in the early online edition of Proceedings of the National Academy of Sciences.