Influenza A virus neuraminidase: regions of the protein potentially involved in virus-host interactions.

Phylogenetically informative amino acid positions (PIPs) were identified in influenza A neuraminidases of subtypes N1 and N2. Neuraminidase evolves in a lineage-specific way as the virus adapts to a new host or changes to evade the host's immune system. Thus, many PIPs undoubtedly identify positions involved in virus-host interactions. Phylogenetically important regions (PIRs) are defined as several PIPs near one another. There are 15 PIRs on N1 and 12 on N2, seven of which are shared between the two subtypes. Many PIRs are coincident with antigenic or glycosylation sites. Other PIRs may represent additional antigenic sites or may be involved in other aspects of virus-host biology.