FI6 (antibody)

FI6 is a broadly neutralizing antibody (bnAb) targeting influenza A viruses, particularly the hemagglutinin (HA) protein. It exhibits cross-reactivity across multiple influenza A subtypes, including H1N1, H2N2, H3N2, H5N1, H7N9, and H9N2.

FI6’s mechanism of action involves binding to a conserved region on the HA stem domain, which is less susceptible to antigenic drift compared to the globular head region. This conserved binding site contributes to its broad neutralization capabilities. Specifically, FI6 recognizes a helical coiled-coil structure within the HA stem, inhibiting the conformational changes required for membrane fusion and viral entry into host cells.

The identification and characterization of FI6 and similar broadly neutralizing antibodies have advanced our understanding of influenza virus immunology and have informed the development of novel influenza vaccines and therapeutics. Research efforts are ongoing to utilize FI6's structural information and binding properties to design more effective and universal influenza vaccines that can provide broader and longer-lasting protection against diverse influenza strains.