Hemagglutinin+and+Neuraminidase

 Hemagglutinin

Hemagglutinin (HA) is one of the most defining characteristics of the Influenza virus. Hemagglutinin is an antigenic glycoprotein which is housed on the topical layer of the //Influenza// virus' lipid membrane and is responsible for performing two crucial functions.1.4]

Hemagglutinin’s first function is vertebrate cell recognition. The host cells which //Influenza// can infect will vary depending on the hemagglutinin type on the particular strain of the virus. This virus-cell recognition is accomplished by the hemagglutinin’s propensity to bind to those cells’ sialic (neuraminic) acid-containing receptors.1,3,5]

The second function of hemagglutinin is in the binding of the virus to the host cell. Hemagglutinin facilitates this process by fusing the viral membrane with the target, epithelial cells’ membrane. This fusion happens on areas called endosomes, which are sites that facilitate endocytosis. Endosomes and are found throughout the external membrane of eukaryotic cells. 1,2,10] = = Neuraminidase

Viral neuraminidase (NA) is the second component of the //Influenza// virus’ external membrane. Neuraminidase is an enzyme found on the surface of //Influenza// viral cells and performs the function of cleaving sialic acid receptors and binding sites from the host cell’s glycoproteins. This cleaving of binding receptors is a crucial component of the viral replication cycle as it enables and facilitates the release of the viral progeny and enables them to go on and infect new cells.11]