Hemagglutinin (HA) of Influenza A virus (H1N1) pandemic 2009 strain (HA)

The Hemagglutinin (HA) of the Influenza A H1N1 pandemic 2009 strain (H1N1pdm09) is a class I viral fusion protein and the primary surface antigen of the virus (UniProt P03452). It mediates viral entry by binding to alpha-2,6-linked sialic acid receptors, which are prevalent in the human upper respiratory tract, facilitating the initial attachment of the virus to host cells (PubMed: 19443736). Following endocytosis, the low pH environment of the endosome triggers a dramatic conformational rearrangement in the HA protein, leading to the fusion of the viral and endosomal membranes and the subsequent release of the viral genome into the host cytoplasm (NCBI: Influenza Virus). As the major target of the host's neutralizing antibody response, HA is the central focus of vaccine development and a key site for monitoring antigenic drift and shift (CDC: Influenza Vaccines). Current therapeutic strategies include the use of small-molecule inhibitors like Umifenovir that block the fusion process and the development of broadly neutralizing monoclonal antibodies targeting the conserved stem region of the HA molecule (PubMed: 30104374).

Other names

H1 HAHemagglutinin proteinHA1/HA2H1N1pdm09 HASurface glycoprotein

Inhibition of viral attachment to host cell sialic acid receptors or prevention of the pH-dependent conformational change required for membrane fusion.