Ibv Hemagglutinin 1

Hemagglutinin (HA) is a single-pass type I integral membrane glycoprotein from the influenza virus, and comprises over 80% 0f the envelope proteins present in the virus particle. In natural infection, in active HA is matured into HA1 and HA2 outside the cell by one or more trypsin-like, arginine-specific endoprotease secreted by the bronchial epithelial cells. Binding of HA; tosialicacid-containing receptor sonthe surface of its target cell brings about the attachment of the virus particle to the cell and forms a endosome. Low pH in endosomes induce an irreversible conformational change in HA2, releasing the hydrophobic portion fusionpeptide. After which, virus penetrates the cell and pours its contents including the RNA genomeinto the cytoplasm mediated by fusion of the endocytosed virus particle own membrane and theendosomal membrane. Hemagglutinin plays a major role in the determination of host range restriction and virulence. Influenza B viruses are only known to infect human sandseals, and evolves lower than A viruses.