Definition for View source for Hemagglutinin

Hemagglutinin refers to a substance that causes red blood cells to agglutinate. This process is called hemagglutination. 

The structure of Hemagglutinin is very similar between strains, and differs in only a few structural difference. What makes this strain differ from the H5N1 [[influenza]] now posing a pandemic threat is the speficity of its binding regions, which will be the basis of this study. What makes this strain of influenza so dangerous is both its rapid ability to evolve and the fact that mammals, specifically humans contain to immune defenses against this avian strain. In 1918, a strain of influenza A virus killed 20-40million people worldwide and the World Health Organization estimates nearly 7 million dead and 1 billion ill from an outbreak of the current H5N1 strain.

==== Why look at Hemagglutinin? ====

Researchers have been able to determine that Hemagglutinin (HA) is a species specific binding protein that allows for the virus to bind to the cell membrane of host respiratory cells and propagate through cellular processes. By examining this process, medical researchers hope to determine a vaccine that may prevent this binding from occurring, thus preventing host infection.