Flu Dynasty: Influenza Virus In 1918 And Today

[Adsos Letter]

Source: Science Daily
(June 30, 2009) — The influenza virus that wreaked worldwide havoc in 1918-1919 founded a viral dynasty that persists to this day, according to scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

In an article published online on June 29 by the New England Journal of Medicine, authors Anthony S. Fauci, M.D., Jeffery K. Taubenberger, M.D., Ph.D., and David M. Morens, M.D., argue that we have lived in an influenza pandemic era since 1918, and they describe how the novel 2009 H1N1 virus now circling the globe is yet another manifestation of this enduring viral family.

"The 1918-1919 influenza pandemic was a defining event in the history of public health," says NIAID Director Dr. Fauci. "The legacy of that pandemic lives on in many ways, including the fact that the descendents of the 1918 virus have continued to circulate for nine decades."

Influenza viruses have eight genes, two of which code for virus surface proteins—hemagglutinin (H) and neuraminidase (N)—that allow the virus to enter a host cell and spread from cell to cell. There are 16 H subtypes and 9 N subtypes, and, therefore, 144 possible HN combinations. However, only three (H1N1, H2N2 and H3N2) have ever been found in influenza viruses that are fully adapted to infect humans. Other combinations, such as avian influenza H5N1, occasionally infect people, but they are bird viruses, not human viruses.

http://www.sciencedaily.com/releases/2009/06/090629200643.htm