Host cell pathway controlling influenza hemagglutinin post-translational maturation (HA maturation pathway)

The host cell pathway controlling influenza hemagglutinin (HA) post-translational maturation is a critical sequence of host-mediated biochemical events required for the production of infectious influenza virus particles. This pathway begins in the endoplasmic reticulum (ER), where the HA precursor (HA0) undergoes folding and trimerization assisted by host chaperones like Calnexin and Calreticulin, followed by N-linked glycosylation and palmitoylation. The most pivotal step for viral infectivity is the proteolytic cleavage of HA0 into the HA1 and HA2 subunits by host cell proteases, such as TMPRSS2, HAT (TMPRSS11D), or Furin. This cleavage exposes the fusion peptide at the N-terminus of HA2, which is essential for the virus to fuse with the host endosomal membrane and release its genetic material into the cytoplasm. Because the influenza virus relies entirely on host machinery for these maturation steps, targeting components of this pathway represents a promising host-directed antiviral strategy. Drugs such as camostat and nafamostat inhibit the proteases required for HA activation, while others like nitazoxanide interfere with the intracellular trafficking and glycosylation of the protein. This approach is particularly valuable because host-directed therapies typically exhibit a higher barrier to the development of viral resistance compared to traditional drugs that target rapidly mutating viral proteins.

Other names

Influenza hemagglutinin maturation pathwayHost cell protease-mediated HA cleavage pathwayHA0 processing pathwayHemagglutinin post-translational modification pathway

Inhibition of host cell enzymes and chaperones involved in the folding, glycosylation, trafficking, and proteolytic cleavage of the influenza hemagglutinin precursor (HA0). Key mechanisms include the inhibition of host proteases (e.g., TMPRSS2, Furin) to prevent HA0 cleavage into HA1 and HA2 subunits, and the inhibition of ER-resident enzymes (e.g., glucosidases) or trafficking pathways (e.g., by Nitazoxanide) to prevent proper HA maturation and surface expression.