Influenza Hemagglutinin Binding and Interactions with a Host Cell

Abstract

The CDC estimates that during the flu season 35 to 50 million people get the flu. Hemagglutinin (HA) is one of the main proteins required for influenza virus to infect host cells. Located on the surface of the virus, HA is responsible for binding the virus to the cell, and for releasing the viral genome into the host cytoplasm. There are 17 different HA subtypes (HA1 ‐ HA17), but HA1, 2, and 3 are the only strains specific to human influenza. Even though they appear in different animals, HA binds to sialic acid, which is present on the surface of epithelial cells in the upper respiratory tract. HA is a trimer protein made of a globular and stem domain. The sialic acid binding region resides in the globular head. The binding depression surrounds the sialic acid domain with three identical primary regions. These regions are comprised of a loop‐helix‐ loop structure, which surrounds the sialic acid, forming the triangular opening into the beta‐sheet depression. The exact binding geometry between hemagglutinin and cell surface proteins differs within species, thereby accounting for the species specificity of HA. The Olathe North SMART team (Students Modeling a Research Topic) modeled HA using 3D printing technology. Program supported by a grant from NIH‐SEPA.