Surface Proteins: Key to Understanding the Bird Flu Epidemic

By Akari Miki

Influenza viruses that infect birds are widespread and devastating – it was estimated that the H5N8 avian influenza resulted into a loss of at least $5 billion for the American poultry industry in 2015. The factors that enhance the adaptability and persistence of the avian influenza have been largely unknown, but recent studies suggest that the key may be hemagglutinin 5 (H5), a type of surface protein on viruses. H5 has been found on H5N1, a strain that caused an epidemic among domestic birds in 1977, and H5Nx, a new group. According to a collaborative study between Utrecht University in the Netherlands and the Scripps Research Institute in La Jolla, California, H5N1 has gained genetic mutations that altered the structure of H5. In a recent commentary published in Emerging Infectious Diseases, influenza experts at the National Institute of Allergy and Infectious Diseases (NIAID) went further by examining how the evolution of the protein structure resulted into the emergence of H5N1: the alteration allowed H5 to attach to new cell receptors of host cells. As the result of this evolution, the avian influenza virus can infect a larger variety of birds and spread rapidly. To humans, this can be good news, because this adaptation may reduce the ability of the virus to infect mammals. However, there may be unknown cell receptors in the respiratory tracts to which H5 can bind, enabling the possibility for H5Nx to impact people.


NIH/National Institute of Allergy and Infectious Diseases. "Evolution of avian influenza examined." ScienceDaily. ScienceDaily, 18 January 2017. <>.