Influenza A virus H7N9 hemagglutinin (HA (H7N9))

Influenza A virus H7N9 hemagglutinin is a trimeric glycoprotein found on the surface of avian-origin H7N9 influenza A viruses, serving as the key viral attachment and fusion protein mediating infection of host cells[1][3][4]. It binds sialic acid-containing glycan receptors on host respiratory epithelial cells through its globular head domain, enabling viral entry, and catalyzes the fusion of viral and host membranes via its stem region following endosomal acidification[1][3]. Hemagglutinin is also the primary antigen recognized by the host immune system, and variations in its structure underlie both immune escape and zoonotic emergence[4][5]. H7N9 hemagglutinin is a pandemic concern due to its capacity to infect both birds and humans and its ongoing evolution toward enhanced binding of human-type receptors[2][4][6]. It is a major focus for vaccine development, antibody therapeutics, and surveillance efforts due to its essential role in influenza A virus infectivity and transmission[1][5][6].

Other names

Hemagglutinin (H7N9)H7N9 HAInfluenza H7N9 hemagglutininAvian influenza A H7N9 hemagglutinin

Inhibition of receptor binding or membrane fusion (for anti-HA antibodies); Neutralization of viral infectivity by antibody-mediated blocking of sialic acid binding site or preventing post-binding conformational changes; Immune response priming or boosting (for vaccine antigens)