FIGURE 1-5. Change in hemagglutinin (HA) and neuraminidase (NA) proteins over time.

FIGURE 1-5

Change in hemagglutinin (HA) and neuraminidase (NA) proteins over time. The number of amino acid changes from a hypothetical ancestor was plotted versus the date of viral isolation for viruses isolated from 1930 to 1993. Open circles, human HA; closed diamonds, human NA; closed circles, swine HA; open diamonds, swine NA. Regression lines were drawn, extrapolated to the x-intercept and then the 1918 data points, closed square, 1918 HA; closed circle, 1918 NA were added to the graph (arrow).

SOURCES: Reid et al. (1999, 2000); Taubenberger et al. (2000).

From: 1, The Story of Influenza

Cover of The Threat of Pandemic Influenza
The Threat of Pandemic Influenza: Are We Ready? Workshop Summary.
Institute of Medicine (US) Forum on Microbial Threats; Knobler SL, Mack A, Mahmoud A, et al., editors.
Washington (DC): National Academies Press (US); 2005.
Copyright © 2005, National Academy of Sciences.

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