Bats reveal the true power of influenza A virus adaptability
Fig 2
Model of the receptor binding and modulating activity of the known IAV surface glycoproteins.
(A) Infection of a host cell is initiated by binding of HA subtypes H1–16 to sialic acid residues exposed on the host cell surface. These glycan structures are subsequently cleaved off by NA of the subtypes N1–9 in order to facilitate the release of viral particles. (B) The H17 and H18 HA proteins of New World bat IAVs utilize MHC-II molecules for cell entry. Preliminary data suggest that the New World bat IAV N11 NA protein decreases MHC-II surface expression by a yet unknown mechanism, allowing unhindered release of budding particles. (C) The New World bat IAV subtype H18N11 exhibits an unforeseen high flexibility to quickly acquire H18mut that compensate for an N11trunc and restore efficient growth in cell culture and mice. (D) This inherent flexibility of H18 might have the potential to allow further adaptations to new cell surface receptors. H18mut, mutations in H18; HA, hemagglutinin; IAV, influenza A virus; MHC-II, major histocompatibility complex class II; N11trunc, truncated N11; NA, neuraminidase.